Why Use a LAN?
Information sharing
Having users access the same files, exchange information via
email, or use Internet
Ex: single purchase order database accessed by all users on the
LAN
Results in improved decision making Results in improved decision making
Resource sharing
Having hardware devices shared by all users
Printers, Internet connections
Having software packages shared by all users on a LAN
Results in reduced cost
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LAN Types
Dedicated server network
A server (computer) permanently assigned a specific
task
Most popular network type
90% of all LANs 90% of all LANs
Peer-to-peer network
No dedicated servers used
All computers act as both clients and servers
Cheaper than dedicated, but less capability
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Dedicated Server Networks
Requires one or more dedicated computers (servers)
Permanently assigned a specific task (Web server, e-
mail server, file server or print server)
Enable users to share files, printers, etc.,
May form a server farm (many servers part of a May form a server farm (many servers part of a
network)
Runs a server network operating system (NOS)
Windows NT, Windows Server, LINUX
Also requires a special communication software to
enable communications with client computers
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Types of Dedicated Servers
Common Types:
Web servers, e-mail servers, database servers
Others
File servers
Allows many users to share the same files on a common disk drive
Typically with restricted access
Print servers
Handle print requests
Could be a separate computer
Remote Access Servers
Enable users to dial in the LAN by phone (via modems)
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Components of a Local Area Network
SWITCH L2
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Local Area Network (LAN) in a large building
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Project 802 by IEEE: standards to enable communication among equipments:
Its a way of specifying functions of the physical layer and
the data link layer of major LAN protocols.
IEEE subdivided data link layer:
Logical Link Control (LLC), Media Access Control (MAC).
Wired LANs
- LLC provides one single data link control protocol for
all IEEE LANs.
- MAC provides different protocols for different LANs.
MAC defines specific access method for
each LAN:
- MAC provides different protocols for different LANs.- CSMA/CD
for Ethernet LAN,
- Token passing
for token ring,
-
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Wired LANs: Ethernet
Ethernet is the most widely used local area network protocol
Ethernet LAN is defined by IEEE 802.3 standard,
it uses 1-persistent CSMA/CD as the access method.
The MAC sublayer is responsible for the operation of
the CSMA/CD.
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Wired LANs: Standard Ethernet
Standard Ethernet 802.3 frame format
Each station has a unique 48-bit address imprinted on its Network Interface Card (NIC).
Example of an address in hexadecimal notation:
Frame length: The minimum frame length is 64 bytes; the maximum is 1518 bytes.
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Wired LANs: Standard Ethernet
Categories of Standard Ethernet
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10Base5 implementation
Wired LANs: Standard Ethernet
10Base2 implementation11
Wired LANs: Standard Ethernet
10Base-T implementation
10 Base T switch
10Base-F implementation
10 Base T switch
10 Base F switch 12
Summary of Standard Ethernet implementations
Wired LANs: Standard Ethernet
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Wired LANs: Ethernet evolution
Sharing bandwidth.
Collision domains in an unbridged
network and a bridged network.
Bridged Ethernet
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Wired LANs: Ethernet evolution
Switched Ethernet
Full-duplex switched Ethernet
CSMA/CD ?
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Wired LANs: Fast Ethernet
Fast Ethernet 802.3u
Upgrade the data rate to 100 Mbps.
Star topology only.
Compatible with standard Ethernet.
Keep: - the same frame format,
- the same minimum and maximum frame length.
Autonegotiation.
Fast Ethernet implementations
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Wired LANs: Fast Ethernet
Summary of Fast Ethernet implementations
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Wired LANs: Gigabit ETHERNET
Gigabit Ethernet 802.3z
Upgrade the data rate to 1 Gbps.
Star topology only.
Compatible with standard and fast Ethernet.
Keep: - the same frame format,
- the same minimum and maximum frame length.
Autonegotiation.
Gigabit Ethernet implementations
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Wired LANs: Gigabit ETHERNET
Summary of Gigabit Ethernet implementations
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Wired LANs: Ten-Gigabit ETHERNET
Ten- Gigabit Ethernet 802.3ae
Upgrade the data rate to 10 Gbps.
Star topology only.
Compatible with standard, fast, and Gigabit Ethernet.
Keep: - the same frame format,
- the same minimum and maximum frame length.
Summary of Ten-Gigabit Ethernet implementations
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