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1
CSCD 433Network ProgrammingFall 2011
Lecture 6Ethernet Evolution and Performance
Topics
bull Ethernet Revisitedbull Faster and Faster Ethernetbull Up to 10 Gigabit and beyond
2
Ethernet Performance
bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA
bull Since the 1970s Ethernet has become fasterbull Why
Ethernet
1 Changes in physical medium Coaxial UTP cables Fiber optic
2 Improved media access control methods CSMA to CSMACD to none needed
3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more
4 Cables to hubs to switches
5 Mandating Full Duplex
Ethernet Speedup
History of Ethernet
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Topics
bull Ethernet Revisitedbull Faster and Faster Ethernetbull Up to 10 Gigabit and beyond
2
Ethernet Performance
bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA
bull Since the 1970s Ethernet has become fasterbull Why
Ethernet
1 Changes in physical medium Coaxial UTP cables Fiber optic
2 Improved media access control methods CSMA to CSMACD to none needed
3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more
4 Cables to hubs to switches
5 Mandating Full Duplex
Ethernet Speedup
History of Ethernet
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Ethernet Performance
bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA
bull Since the 1970s Ethernet has become fasterbull Why
Ethernet
1 Changes in physical medium Coaxial UTP cables Fiber optic
2 Improved media access control methods CSMA to CSMACD to none needed
3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more
4 Cables to hubs to switches
5 Mandating Full Duplex
Ethernet Speedup
History of Ethernet
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
bull Ethernet was designed by Bob _________ in 1973 at the Xerox Company in Palo Alto CA
bull Since the 1970s Ethernet has become fasterbull Why
Ethernet
1 Changes in physical medium Coaxial UTP cables Fiber optic
2 Improved media access control methods CSMA to CSMACD to none needed
3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more
4 Cables to hubs to switches
5 Mandating Full Duplex
Ethernet Speedup
History of Ethernet
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
1 Changes in physical medium Coaxial UTP cables Fiber optic
2 Improved media access control methods CSMA to CSMACD to none needed
3 Improved signal encoding methods Manchester encoding to 4B5B 8B10B and more
4 Cables to hubs to switches
5 Mandating Full Duplex
Ethernet Speedup
History of Ethernet
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
History of Ethernet
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
7
An Introduction of Ethernet
bull The History of Ethernet Technology
ndash 1973 Metcalfe developed Ethernet at Palo Alto
ndash 1980 Digital Intel and Xerox developed the standard of 10Mpbs Ethernet
ndash 1992 the Grand Junction Network Company brought up the structure of 100Mbps Ethernet
ndash 1998 addressed the standard of Gigabit Ethernet
ndash 2002 10 Gigabit standard httpwwwtrendcommscommultimediatrainingbroadband
20networkswebmainethernetthemechapter1EnetIntroductionhtml
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Classical or Standard Ethernet
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
9
Categories of Standard Ethernet
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Ethernet Recap
bull Classic Ethernet bull One long cable 500 meter max segmentbull Snaked around building as single long cablebull All computers attached
bull Thick Ethernetbull Began as thick yellow cable marked every
25 meters to show computer attachments
bull Thin Ethernetbull Thinner bent more easily connections with
BNC connectorsbull Cheaper to install 185 meter max segment
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
11
10Base5 implementation
Ethernet segment length
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
12
10Base2 Implementation
Ethernet segment length
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
13
bull Coaxial cable has single copper conductor at its center
bull A plastic layer provides insulation between center conductor and a braided metal shield
bull Metal shield helps to block any outside interference from fluorescent lights motors and other computers
bull Resistant to signal interference and can support greater cable lengths between network devices than twisted pair cable
bull Only half-duplex is possible with coaxial cable
EfficiencyCoaxial Cable
A outer plastic sheathB woven copper shieldC inner dielectric insulatorD copper core
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
14
10Base-T implementation
UTP = Unshielded Twisted Pair
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
15
Efficiency Twisted Pairbull Twisted pair cabling comes in two varieties
Shielded and Unshielded Unshielded twisted pair (UTP) is the most popular bull Cable has four pairs of wires inside jacketbull Each pair twisted with different number of
twists per inchbull Eliminate interference from adjacent pairs
and other electrical devicesbull Tighter twisting higher supported
transmission rate and greater cost per footbull Most important
bull Two connections for each host Full duplex is now possible
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
2 Pairs of Wires in a UTP Cable Are Always Used
No matter whether the device is a hub or a switch 2 pairs of wires in a UTP cable are always used to connect a host to the device
2 pairs
12- 16
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
17
Efficiency Twisted Pair
Category Speed Use
1 1 Mbps Voice Only (Telephone Wire)
2 4 Mbps LocalTalk amp Telephone (Rarely used)
3 16 Mbps 10BaseT Ethernet
4 20 Mbps Token Ring (Rarely used)
5 100 Mbps (2 pair) 100BaseT Ethernet
1000 Mbps (4 pair) Gigabit Ethernet
5e 1000 Mbps Gigabit Ethernet
6 10000 Mbps Gigabit Ethernet
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
18
Ethernet CablingThe most common kinds of Ethernet cabling
Three kinds of Ethernet cabling
(a) 10Base5 (b) 10Base2 (c) 10Base-T
Difference in Segment length
Costs Less
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Ethernet Recap
bull Used Manchester encoding bull More later
bull Ethernet could contain multiple segments and multiple repeaters
bull Used CSMACD for shared media bull What does CSMACD stand for
Carrier Sense Multiple AccessCollision Detection
bull Review this
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
20
CSMACD Protocol
All hosts transmit amp receive on one channelPackets are of variable size
When a host has a packet to transmit1 Carrier Sense Check that the line is quiet before
transmitting2 Collision Detection Detect collision as soon as possible Collision is detected stop transmitting wait a random
time then return to step 1 binary exponential backoff
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
21
Ethernet CSMACD algorithm
Algorithm1 NIC receives datagram from network
layer creates frame
2 If NIC senses channel idle starts frame transmission
If NIC senses channel busy waits until channel idle then transmits
3 If NIC transmits entire frame without detecting another transmission NIC is done with frame
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Ethernet CSMACD algorithm
4 If NIC detects another transmission while transmitting aborts and sends jam signal5 After aborting NIC enters exponential backoff after mth collision NIC chooses a K small integer at random from 012hellip2m-1 NIC then waits K512 bit time
bull Returns to Step 2
22
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Minimum Frame Size
bull In order to allow collision detection frames must have a Minimum Frame Size (MFS)
bull Consequently small frames must be padded out to reach MFS
bull MFS (bits) is related to length of the LAN and transmission rate (bitssec)
bull Ethernet and Fast Ethernet the MFS is 64 bytes
bull Gigabit Ethernet it is 416 or 520 bytes
bull Full duplex versions of Ethernet
bull Collisions are avoided and so MFS does not apply
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Ethernet Performancebull One result of sharingldquoEtherrdquo
bull More stations on an Ethernet networkbull Higher number of collisionsbull Worse performance
bull Typical performancebull 10-Mbps Ethernet networkbull Around 100 stationsbull Supports a bandwidth of only about 40 to 60
percent of the expected value of 10 Mbpsbull How would you increase performance
bull Fewer Collisions reduce the collision domain
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernet
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernet 8023u
bull When switches became popular bull 10 Mbps Ethernet was standard back in
1995bull How to make Ethernet fasterbull Fast Ethernet proposed by IEEE
Committeebull Wanted speeds of 100 Mbps bull Old standard 8023bull New amended standard 8023u
bull Not really New - Kept everything the same
bull Why might you want to do thisbull Backward compatibilitybull Golden rule of Computer Science
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernetbull Primary concern of Fast Ethernet developers
bull Preserved CSMACD medium access method of 8023 Ethernet while boosting data rate
bull Point is to make it FASTERbull Kept frame formatbull Wanted Fast Ethernet fit within traditional
Ethernet installationsbull One version of the Fast Ethernet standard
runs on older Category 3 cable installations
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernet
bull Another important ideabull Multiple Ethernet types 10 and 100 Mbps
could coexist
bull How bull A Fast Ethernet-compatible hub does speed
matching when exchanging framesbull Has auto-negotiate feature
bull Devices detect speed of incoming transmissions and adjust appropriately
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
29
IEEE 8023u - Fast Ethernet
bull Technically IEEE 8023u is not a new standard but an addendum to IEEE 8023 standard
bull Transmission rate is 100 Mbps
bull Fast Ethernet is only defined for star topology LANs (ie shared-medium hubs and switching hubs)
bull Uses category 3 and category 5 UTP STP and fibre cables
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernet Four Schemesbull 100Base-TX Runs on two pairs of Category 5
data-grade twisted-pair wire max distance 100 meters between hub and workstation
bull 100Base-T4 Runs on four pairs of cable including Category 3 cable max distance 100 meters between hub and workstation
bull 100Base-FX Runs on optical cable at distances up to 2 kilometers used to connect hubs over long distances in a backbone configuration
bull 100Base-SX Called Short Wavelength Fast Ethernet for a Fast Ethernet over fiber-optic cable using 850 nm wavelength optics
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fiber Optic Cablingbull Fiber optic cabling consists of center glass
core surrounded by layers of
protective materials bull Fiber optic cable transmits signals over longer
distances than coaxial and twisted pairbull Signals consist of light instead of electrical pulsesbull Has capability to carry information at greater
speedsbull Center core of fiber cables is made from glass or
plastic fibers plastic coating then cushions fiber center and kevlar fibers help to strengthen cables and prevent breakage
bull Outer insulating jacket made of teflon or PVC
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fiber Optic Cabling
bull Two types of fiber cables
bull Single mode
bull Multimode
bull Multimode cable has larger diameter allows light take different paths has more trouble with attenuation
bull Both cables provide high bandwidth at high speeds
bull Single mode can provide more distance but it is more expensive
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernetbull Higher frequency used in Fast Ethernet
standard is prone to attenuation
bull Cable distance is more limited than in old Ethernet 10Base-T
bull If encoding scheme of traditional Ethernet were used with Fast Ethernet
bull High-end frequency would be above 200 Mhz
bull Double maximum frequency rating of Category 5 cable
bull New encoding schemes were implemented to allow higher-frequency transmissions
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Encoding Schemes for Ethernet
bull Manchester Encoding Standard Ethernetbull Synchronous clock encoding technique used by
physical layer
bull Recall Manchester encoding
bull 0 is indicated by a 0 to 1 transition at center of bit
bull 1 is indicated by a 1 to 0 transition at center of bit
bull Manchester encoded signal contains frequent level transitions allows receiver to extract the clock signal and correctly decode the value and timing of each bit
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
bull Manchester Encodingbull Up transition = 1
bull Down transition = 0
Manchester EncodingStandard Ethernet
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Manchester EncodingStandard Ethernet
bull Drawbackbull Manchester encoding can consume up to
approximately twice bandwidth of original signal (20 MHz)
bull Penalty for introducing frequent transitions
bull For a 10 Mbps LAN the signal spectrum lies between the 5 and 20 MHz
bull Additional bandwidth is not significant issue for coaxial cable transmission but
bull CAT5e cable bandwidth more limitedbull Needed more efficient encoding method
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernet Encoding
bull 4B5B encoding is a type of Block coding
bull Processes groups of bits rather than outputting a signal for each individual bit (as in Manchester encoding)
bull Group of 4 bits encoded so that an extra 5th bit is added
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
bull 4B5B encoding (Frame Encoding ndash shorthand)
bull All data is encoded prior to transmission
bull Every 4 bit group (16 different combinations) is mapped onto a 5 bit code (symbol)
bull 5B symbols for 4B data groups are chosen such that a maximum of 2 successive zeros occur
bull 5B symbols which are not used for data encoding are used as control symbols - symbols such as 0001 00010 are not used
bull Multi-Level Transmit-3 levels
bull No transition = 0
bull Any transition (up or down) = 1
bull Reduces frequency of signal
Fast Ethernet Encoding
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernet Encodingbull Thus 100 Mbps transmission
bull Uses a 4b5b MLT code
bull Uses three signal levels and allows a 100 Mbps signal to occupy only 31 MHz of bandwidth
bull Gigabit Ethernet
bull Uses five levels and 8b10b encoding to provide even more efficient use of the limited cable bandwidth
bull 1 Gbps within 100 MHz of bandwidth
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Fast Ethernetbull Fast Ethernet supports Full-Duplex switched
mode to provide even better performancebull A full-duplex nonshared link
bull Dont need CSMACDbull Each end system has its own channelbull Collision detection and loopback functions
can be disabled bull If both end systems are transmitting at
same time combined data rate is 200 Mbps
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
All Gigabit Ethernet
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Gigabit Ethernetbull Yet more speed
bull More modified standards 1998 - 1999bull 8023z which required optical fiber and 802ab over UTP
bull Gigabit Ethernet is 1 Gbps or 1000 Mbps extension of IEEE 8023 Ethernet networking standardbull Primary niches corporate LANs campus networks
and service provider networksbull Can be used to tie together existing 10 and 100
Mbps Ethernet networksbull Gigabit Ethernet competes with ATM
(Asynchronous Transfer Mode) as core networking technology
bull Many ISPs use Gigabit Ethernet in their data centers
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Gigabit Ethernet Extensionsbull Gigabit Ethernet Required Changes
1 Increased frame size beyond 1500 bytesbull Can have Jumbo frames of up to 9000 bytesbull Idea is that at higher speeds it makes sense
to have larger framesbull Transmitting larger frames means fewer
CPU interrupts and more data getting through instead of more headers
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Gigabit Ethernet Extensions
bull Also mixing classic Ethernet with Gigabit Ethernet buffer overruns are likely
bull So flow control is supported
bull One end sends control frame telling it to pause for a time
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Pause Function
bull Implement a simple ldquostop-startrdquo flow control schemebull If a device wants to temporarily inhibit incoming frames it sends a PAUSE frame to the full-duplex partnerbull PAUSE frame contains a parameter indicating the length of time the partner should wait before sending more frames
12- 45
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
10 Gigabit Ethernet
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
47
Easy Migration to Higher Performancebull 10 Gigabit Ethernet
ndash Is simplest way to scale enterprise and service provider (SP) networks
ndash Leverages installed base of more 300 million Ethernet switch ports
ndash Supports all data servicesndash Supports local metro and wide area
networks
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
48
Easy Migration to Higher Performance
ndash Is faster cheaper and simpler than alternatives
ndash Optionally matches MANWAN backbone speed of OC-192
bull Promises ability for Ethernet to use SONETSDH for Layer1 transport across WAN transport backbone
bull SONET Synchronous Optical NETwork
bull SDH equivalent Synchronous Digital Hierarchy network
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
49
Low Cost of Ownership
bull Each new generation of Ethernet provides 10 times the bandwidth at only three to four times the cost of the previous generation
bull 10 Gbps WAN PHY links will cost less than 10 Gbps OC-192c linksndash 10 Gbps WAN PHY is an asynchronous
Ethernet linkndash SONETSDH is difficult expensive to
implement timing and jitter requirement
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
50
Ethernet Economics
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
51
Application for 10 Gigabit Ethernet
bull 10 Gigabit Ethernet in LAN
bull 10 Gigabit Ethernet in MAN
bull 10 Gigabit Ethernet in WAN
bull 10 Gigabit Ethernet in SAN
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
52
10 Gigabit Ethernet in LAN
bull Campus Backbonendash Higher speed links
bull Inter-Campusndash Long distance connectivity
bull Server Farmndash Higher bandwidth contentndash Broadband Access driven demand to amp from
servers
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
53
10 Gigabit Ethernet in LAN(cont)bull Extended Storage Area Networks
ndash Meeting SAN QoS requirements across WANs
bull Removal of LAN bottlenecks
bull Eliminate of 1Gbps link aggregation issues
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
54
10 Gigabit Ethernet in LAN(cont)
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
55
10 Gigabit Ethernet in MAN
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
56
10 Gigabit Ethernet in WAN
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
57
10 Gigabit Ethernet in WAN(cont)
bull Seamless access to the optical infrastructure
bull Simple very high speed low cost interintra-PoP connection
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
References
Encoding Schemes (very thorough)httpgbenthiennetencodingpdf
Cablinghttpfcitusfedunetworkchap4chap4htm
Ethernet Encoding SchemeshttpfengnetcombookCNF
ch02lev1sec1html
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
Summary
bull Ethernet has evolved over many yearsbull Physical cabling changes in encoding
changing Media Access has allowed Ethernet to change with changes in technology
bull Managed to maintain its cost-effectiveness in the face of competing technologies
60
bull Assignmentbull Problems from the Book
60
bull Assignmentbull Problems from the Book