ATM in TCP/IP ATM in TCP/IP environmentenvironment: : AdaptationsAdaptationsand and EffectivenessEffectivenessDipl.-Ing. Kai-Oliver Detken, BIBAATM Traffic Symposium, Mykonos, Greece, September the 17th, 1997
Bremen Institute of Industrial Technology and Applied Work Science
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ContentContent• Introduction of the European ACTS project EIES
(European Information Exchange Service)• IP-over-ATM difficulty• IP-over-ATM possibilities: Classical IP, LAN
Emulation (LANE), and MPOA• IP effectiveness: protocol overhead, TCP throughput
obstacles, sender and receiver buffers, RTT and MTU deadlocks, UDP and Client performance
• Performance Improvements and further developments
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TheThe ACTS ACTS projectproject EIES EIES
• Definition, implementation, and experimentation of advanced telecommunication services
• Support routine and non-routine communicationbetween different maritime players
• Define and transpose the user requirements for theservice development of EIES
• Build-up a pre-commercial global EIES service• Establish an ATM link between the different
harbour sites (Bordeaux, Bremen, Brest, Santander) to use the prototypes in real life
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EIES EIES servicesservices• Computer Supported Cooperative Work (CSCW)• Distribution of multimedia information about
different databases (BluePages and Port EntryGuide)
• Integration of Electronic Data Interchange (EDI) and Electronic Mail (Email)
• Mobile communication (DSRR, DECT, and Inmarsat) for the mobile access to the services.
• Fixed networks: ATM, ISDN, and Internet (IP)
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EIES EIES platformplatform
LAN 2
Remote Client
LAN 1
ATM
IP Router
Mobile Access
LAN Client
Internet Server
Internet
Communications Server Communications Server
Mobile Access
LAN Client
Internet Server
Remote Client
IP Router
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• Internet Protocol works connectionless (hop-by-hop-transmission)
• No acknowledgements, error- and duplicatedetection with IP
• Data packets are variable: 20 byte - 65 kbyte; destination address identified the other client
• Lost data packets have to repeat requested byhigher layer protocols (TCP)
• Multicast/broadcast functions• Type-of-Service (TOS)
IP IP featuresfeatures
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ATM ATM featuresfeatures
• Connection-oriented technologie: virtualconnections will establish for the cell transport(PVC/SVC)
• ATM has its own address structur and routingfunktions
• 53 byte cells with fixed size contain payload and control data
• Point-to-point connections• Quality-of-Service (QoS)
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IPIP--overover--ATM ATM AdaptationsAdaptations• Classical-IP
- IETF: RFC-1577- ATM clients use IP
• LAN-Emulation (LANE)- ATM-Forum- Traditional networks use ATM
• Multiprotocol over ATM (MPOA)- ATM-Forum and IETF protocols- Routing mechanisms will be implemented
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ClassicalClassical--IPIP (RFC(RFC--1577)1577)• RFC-1577: Classical-IP and ARP over ATM• Logical Link Control Encapsulation: Multiple protocols can
be transported over a single connection (RFC-1483)• VC-Based Multiplexing: Single protocol is transported over
an ATM connection (RFC-1483)• D-MTU: 9180 Byte• PVC/SVC connections• Transport over the AAL-5 layer• Point-to-point connections• Address resolution by central ATMARP server
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ClassicalClassical--IPIP architecturearchitecture
ATM
Ethernet
Client 1
Client 2
Server 1ATMARP- ATMARP-
Server 2
Client 1
LIS 1 LIS 2
Router
Control Connection
Data Connection
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EncapsulationEncapsulation (RFC(RFC--1483)1483)
header IP payload
LLC0xAAAA03
OUI0x000000
PID0x0800 IP packet
IP packet with LLC-SNAP header PAD
0-47 byte
LengthDetection CRC-32
headerATM
headerATM ATM payloadATM payload
CPI +CPCS-UU
8 byte
48 byte5 byte
3 byte
20 byte 0-9160 byte
20-9180 byte3 byte 2 byte
IP packet
LLC/SNAP packet
IP
28-9188 byte
AAL-5 packet
ATM cells
1-192 cells
48 byte5 byte
SAR-PDU payloadPT SAR sublayer
header
0 SAR-PDU payloadPT
header
0
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RFCRFC--1577 1577 conclusionsconclusions
• Advantages:- high data throughput by high MTU (9180 byte)- simple and stabile standard
• Disadvantages:- only IP unicast is supported- high manual configuration effort- no multicast/broadcast support- no redundant ATMARP server- direct connections to other LIS subnets is not possible- no QoS
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LAN Emulation (LANE)LAN Emulation (LANE)• Migration of traditional LANs to ATM: Ethernet
switch (layer 2) und router (layer 3) coupling• Universal implementation (MAC layer is emulated):
arbitrary LAN protocols• Using of the application layer without ATM
configuration• Support of PVC/SVC connections• IP multicasting• D-MTU: 1500 byte
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LANE LANE architecturearchitectureLAN Emulation Service
LEC
LAN Emulation Configuration
LAN Emulation Server (LES)
Broadcast and Unknown Server
Direct Data Exchange
Control Connection
Configuration Control
SendSendUnicast Multicast
ConnectionConfiguration Control
Connection
Control Connection
LEC
Server (LECS)
Distributed Control Connection Multicast Control Connection
Distributed Data Connection Multicast Data Connection
(BUS)
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header IP payload
LLCAA AA 03
OUI00 00 00
PID0800 IP packet
IP packet with LLC/SNAP- and additional LAN encapsulation
0-47 byte
LenghtDetectionCRC-32
headerATM-
headerATM-ATM payload
CPI +CPCS-UU
48 byte5 byte
3 byte
20 Byte 0-1472 byte
20-1492 byte3 byte 2 byte
IP packet
LLC/SNAP packet
IP
44-1516 byte
AAL-Typ5 packe
ATM cell
2-32 cells
48 byte5 byte
PAD
IP packet with LLC/SNAP encapsulation
28-1500 byte
LE-header
DestinationAddress
LANE packet
2 byte 6 byte
SourceAddress
6 byte 8 byte
SAR-PDU payloadPT SAR Sublayer
header
0PT
header
0 SAR-PDU payload
ATM payload
Type/Length
2 byte
LANE LANE encapsulationencapsulation
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• Advantages:- integration of traditional networks- transparency for arbitrary network protocols- multicast/broadcast support- automatic configuration
• Disadvantages:- high functionality (layer 2 emulation)- MTU and older network boards limitated throughput- bad scalability- no redundant BUS (overload)- no QoS
LANE LANE conclusionsconclusions
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MPOA MPOA capacitycapacity• Support multiple protocols effective over ATM networks• Distribute the routing functions between route servers• Separate routing from switching functions• Leverage performance and QoS capabilities of ATM network• Direct connections between ELANs rather than passing through
traditional routers• Direct Virtual Channel Connections (VCC) between data
forwarding devices• Interworking with unified routers• Enables subnet members to be distributed across the network• Efficient scalability of the ATM network
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MPOA MPOA architecturearchitecture
IASGCoordinationFunctional
DefaultForwarderFunctional
Group
Edge Device
Workstation
ATM network
ATM-Host
ATM-Host
Token Ring
Kontrollverbindung
Control Connection
Data Connection
Shortcut
Group
Data Connection
Control Connection
Data Connection
Control Connection
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• Multicast Address Resolution Server (MARS)- support of multicasting by additional MARS server
• Next-Hop Resolution Protocol (NHRP)- direct connection between subnets possible
• Resource Reservation Protocol (RSVP)- QoS parameter at connectionsless packets- similar to the UNI signaling
• Private Network-to-Network-Interface (P-NNI)- control data exchange between ATM systems- transparency pass on the virtual connection
ExtensionsExtensions forforMPOA MPOA attemptsattempts
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• Advantages:- QoS is supported for the first time- router bottlenecks are eliminated- management of large networks- build up of VLANs
• Disadvantages:- MPOA is not a full defined spezification (1998)- IETF protocols must further developed- scalability is an extremely complex issue- MPOA does not provide a stable network yet
MPOA MPOA conclusionsconclusions
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IPoverATMIPoverATM--OverheadOverhead• STM-1-Frame (OC-3): 155,52 Mbps• ATM Layer: 149,76 Mbps• Adaptation Layer AAL-5: 135,632 Mbps• LLC/SNAP encapsulation:
- MTU: 576 byte 126,937 Mbps- MTU: 9180 byte 135,22 Mbps- MTU: 65527 byte 135,563 Mbps
• Internet Protocol (IP): 125,2/135,1/135,6 Mbps• Transport Layer: 120,9/134,8/135,5 Mbps• Application Layer via TCP: 116,5/134,5/135,5 Mbps• Application Layer via UDP: 119,1/134,7/135,5 Mbps
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• Socket buffer size at sender/receiver• Network: Maximum Transport Unit (MTU)• Protocol: Maximum Segment Size (MSS)• Sender: using of the Nagle’s algorithm• Round-Trip-Time (RTT)• Receiver: delayed acknowledegements• Sender: Silly Window Syndrom (SWS)• Copy strategy at the socket interface• Network congestion and lost packet notice
TCPTCP--ThroughputThroughput ObstaclesObstacles
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Sender and Receiver Sender and Receiver bufferbuffer
S/E 16kbyte
20kbyte
24kbyte
28kbyte
32kbyte
36kbyte
40kbyte
44kbyte
48kbyte
52kbyte
16 kbyte 15,05 13,60 0,322 0,319 0,319 0,467 0,469 0,466 0,469 0,46920 kbyte 15,99 14,60 15,07 14,87 15,40 14,24 1,095 1,095 0,548 0,54924 kbyte 17,71 16,79 16,74 16,32 17,40 17,31 17,42 17,12 0,760 0,74028 kbyte 16,57 17,69 17,93 18,13 18,36 19,20 19,74 19,78 18,38 18,2032 kbyte 14,63 18,96 18,42 19,23 19,14 19,74 19,96 20,31 19,69 19,1736 kbyte 14,33 19,22 18,12 19,82 19,77 19,92 20,56 20,49 20,13 20,2040 kbyte 15,16 19,34 18,85 19,73 20,11 20,41 20,81 20,74 20,69 20,5744 kbyte 14,80 19,40 18,27 20,39 20,16 20,74 20,99 20,87 20,89 20,7048 kbyte 14,62 19,46 18,34 20,48 20,26 20,41 20,85 20,83 20,93 20,8352 kbyte 13,92 19,41 18,26 20,50 20,06 20,21 20,88 20,91 21,21 21,06
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RTT and MTU RTT and MTU deadlocksdeadlocks
0
10
20
30
40
50
60
0 5 10 15 20 25 30
RTT [10̂ -3 s]Th
roug
hput
[Mbp
s]
MTU 576 byteMTU 1500 byteMTU 9180 byteTCP-Window-Limit
• MTU of 9180 byte has the best performance ifthe RTT is low
• MTU of 1500 byte has the best performance ifthe RTT is high
• If the MTU is smaller as the used packet size: fragmentation and reassembling isnecessary!
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UDP UDP performanceperformance
0
1000
2000
3000
4000
0 10 20
Processor numbers10
-Mbp
s-Et
hern
et [k
byte
]
UDP/IPTCP/IP
• Connectionless structure• UDP has no
acknowledgements, no end-to-end control and no duplicate detection
• Less locking effects forprotect shared protocolstate and data
• Locking Effects limits thedata throughput.
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Client Client performanceperformance
1 2 3 4 5 60
50100150200250300350400450
Late
ncy
Tim
e [µ
s]
1 2 3 4 5 6
Sender (1-3) and Receiver site (4-6)
Single-Copy +Checksum
LANs (1,4Ethernet / 2,5FDDI / 3,6 ATM)
• Operation system (inter-processcommunication)
• Data processing• CPU performance• Memory speed• I/O bus bandwidth• ATM adapter
implementation
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Client TuningClient Tuning
Classical-IP: Throughput of 134,01 Mbps (Sun20-Ultra)LAN-Emulation, test 1: Throughput of 76,30 Mbps (Sun20-Ultra)LAN-Emulation, test 2: Throughput of 117,63 Mbps (Ultra-Ultra)
• Using of the D-MTU value• Path-MTU: max. possible packet size should be switch on
(none fragmentation)• MSS value: 1436 byte for high speed networks• Sender and receiver buffer at least 2 times bigger than MTU
value• Window Scale Option (RFC-1323) higher Window-Size
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......furtherfurther developmentsdevelopments
• Classical-IP, Version 2- distributed ATMARP server
• LANE, Version 2- L-UNI: QoS, multicast, ELAN multiplexing- L-NNI: distributed LES/BUS
• IP-Switching (Ipsilon)- none standard- other proposal Tag-Switching from CISCO