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ATM NetworksSlide 2ATM: OverviewSlide 4ATM InterfacesATM Network InterfacesProtocol LayersSlide 8Cell Header FormatHeader Error CheckConnection IdentifiersVP/VC Assignment/UseOriginal Classes of TrafficAAL 5AAL2Physical Media Dependent LayersSummaryATM : Key ReferencesRaj JainThe Ohio State University1ATM NetworksATM NetworksRaj Jain Professor of Computer and Information SciencesThe Ohio State UniversityColumbus, OH 43210-1277http://www.cse.ohio-state.edu/~jain/Raj JainThe Ohio State University2ATM: OverviewATM Protocol LayersNetwork InterfacesAdaptation LayersPhysical LayersOverviewOverviewRaj JainThe Ohio State University3ATM: OverviewATM: OverviewSTM = Synchronous Transfer Mode, ATM = Asynchronous Transfer ModeAllows any-speed and even variable rate connectionATM = Short fixed size 53-byte cellsConnection oriented  Virtual Channels (VC)Raj JainThe Ohio State University4Labels vs addresses  Better scalability in number of nodes7492Switches vs routers Faster due to fixed size, short address, simplicitySeamless  Same technology for LAN, WAN,Data, voice, video integrationEveryone else is doing itRaj JainThe Ohio State University5ATM InterfacesATM InterfacesPrivateNNIPrivateUNIPublicUNIComputerPrivateSwitchPublicSwitchRouterDigitalServiceUnitDXIB-ICIPublicUNIPublicNNIPrivateUNIPrivateSwitchPublicSwitchB-ICIPublicSwitchRegional CarriersPublicSwitchLongDistanceCarrierComputerComputerRaj JainThe Ohio State University6ATM Network Interfaces ATM Network Interfaces User to Network Interface (UNI): Public UNI, Private UNINetwork to Node Interface (NNI): Private NNI (P-NNI)Public NNI =Inter-Switching System Interface (ISSI)Intra-LATA ISSI (Regional Bell Operating Co)Inter-LATA ISSI (Inter-exchange Carriers) Broadband Inter-Carrier Interface (B-ICI)Data Exchange Interface (DXI)Between routers and ATM Digital Service Units (DSU)Raj JainThe Ohio State University7ATM LayerATM Adaptation LayerPhysicalLayerATM LayerPhysicalLayerATM LayerATM Adaptation LayerPhysicalLayerEnd System End SystemSwitchProtocol LayersProtocol LayersRaj JainThe Ohio State University8Protocol LayersProtocol LayersThe ATM Adaptation LayerHow to break application messages to cellsThe ATM LayerTransmission/Switching/ReceptionCongestion Control/Buffer managementCell header generation/removal at source/destinationCell address translationSequential deliveryRaj JainThe Ohio State University9Cell Header FormatCell Header FormatGFC = Generic Flow Control(Was used in UNI but not in NNI)VPI/VCI = 0/0  Idle cell; 0/n  SignalingHEC: 1 + x + x2 + x8VCI PTIHeader Error Check (HEC)VCIVPI VCIGFC/VPI VPICLPPayloadRaj JainThe Ohio State University10Header Error Check Header Error Check HEC protects header onlyOptional Correction mode: Correct one bit errors if no earlier errorsDiscard cells with bad HECUsed for cell delineation in SONETRecalculated on each hopCorrectionModeDetectionModeErrorOptionally correct if 1-bit errorNo ErrorErrorNo ErrorDropForward ForwardRaj JainThe Ohio State University11Connection IdentifiersConnection IdentifiersEach cell contains a 24/28-bit connection identifierFirst 8/12 bits: Virtual Path, Last 16 bits: Virtual CircuitVP service allows new VC's w/o orders to carriersVC1VC2VC3VC1VC2VC3VC1VC2VC3VP1VP3LinkVP2Raj JainThe Ohio State University12VP/VC Assignment/UseVP/VC Assignment/UseSwitch23 56Video Data37 34VoiceData213452356657661122Port0/370/340/230/56VPI/VCIIn1/230/560/654/76VPI/VCI3456PortOutRaj JainThe Ohio State University13Original Classes of Original Classes of TrafficTrafficClass A Class B Class C Class DTime Sync Yes Yes No NoBit Rate Constant Variable Variable VariableConnection-OrientedYes Yes Yes NoExamples CircuitEmulationComp.VideoFrameRelaySMDSAAL AAL1 AAL2 AAL3 AAL4Raj JainThe Ohio State University14AAL 5AAL 5Designed for data trafficLess overhead bits than AAL 3/4  Simple and Efficient AAL (SEAL)No per cell length field, No per cell CRCPADUserPayloadLength CRC-32Control4220-64kB10PTI bit indicates last cell0-47Raj JainThe Ohio State University15AAL2AAL2Ideal for low bit rate voiceVariable/constant rate voiceMultiple users per VCCompression and Silence suppressionIdle channel suppressionCellHeaderCellHeaderPayload 1PktHdrPayload 2 Payload 3PktHdrPktHdrPayload 1PktHdrPayload 2 Payload 3PktHdrPktHdrPayload 1 Payload 2 Payload 3Raj JainThe Ohio State University16Physical Media Physical Media Dependent LayersDependent LayersMultimode Fiber: 100 Mbps using 4b/5b, 155 Mbps SONET STS-3c, 155 Mbps 8b/10bSingle-mode Fiber: 155 Mbps STS-3c, 622 MbpsShielded Twisted Pair (STP): 155 Mbps 8b/10bCoax: 45 Mbps, DS3, 155 MbpsUnshielded Twisted Pair (UTP)UTP-3 (phone wire) at 25.6 Mbps, 51.84 MbpsUTP-5 (Data grade UTP) at 155 MbpsDS1, DS3, STS-3c, STM-1, E1, E3, J2, n × T1Raj JainThe Ohio State University17SummarySummaryATM Overview: History, Why and WhatProtocol Layers: AAL, ATM, Physical layers, Cell formatInterfaces: PNNI, NNI, B-ICI, DXIRaj JainThe Ohio State University18ATM : Key ReferencesATM : Key ReferencesSee http://www.cis.ohio-state.edu/~jain/atm_refs.htmG. Sackett and C. Y. Metz, “ATM and Multiprotocol Networking,” McGraw-Hill, 1997S. Siu and R. Jain, "A brief overview of ATM: Protocol Layers, LAN Emulation and Traffic Management" Computer Communications Review (ACM SIGCOMM), April 1995. Available at http://www.cis.ohio-state.edu/~jain/ATM Forum specs are available at


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WUSTL CIS 777 - ATM Networks

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