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 University2ATM: OverviewATM Protocol LayersNetwork InterfacesAdaptation LayersPhysical LayersOverviewOverviewRaj JainThe Ohio State University3ATM: OverviewATM: OverviewSTM = Synchronous Transfer Mode, ATM = Asynchronous Transfer ModeAllows any-speed and even variable rate connectionATM = Short fixed size 53-byte cellsConnection oriented Virtual Channels (VC)Raj JainThe Ohio State University4Labels vs addresses Better scalability in number of nodes7492Switches vs routers Faster due to fixed size, short address, simplicitySeamless Same technology for LAN, WAN,Data, voice, video integrationEveryone 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 UNINetwork 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 LayersThe ATM Adaptation LayerHow to break application messages to cellsThe ATM LayerTransmission/Switching/ReceptionCongestion Control/Buffer managementCell header generation/removal at source/destinationCell address translationSequential deliveryRaj JainThe Ohio State University9Cell Header FormatCell Header FormatGFC = Generic Flow Control(Was used in UNI but not in NNI)VPI/VCI = 0/0 Idle cell; 0/n SignalingHEC: 1 + x + x2 + x8VCI PTIHeader Error Check (HEC)VCIVPI VCIGFC/VPI VPICLPPayloadRaj JainThe Ohio State University10Header Error Check Header Error Check HEC protects header onlyOptional Correction mode: Correct one bit errors if no earlier errorsDiscard cells with bad HECUsed for cell delineation in SONETRecalculated on each hopCorrectionModeDetectionModeErrorOptionally correct if 1-bit errorNo ErrorErrorNo ErrorDropForward ForwardRaj JainThe Ohio State University11Connection IdentifiersConnection IdentifiersEach cell contains a 24/28-bit connection identifierFirst 8/12 bits: Virtual Path, Last 16 bits: Virtual CircuitVP 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 5Designed for data trafficLess 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 University15AAL2AAL2Ideal for low bit rate voiceVariable/constant rate voiceMultiple users per VCCompression and Silence suppressionIdle channel suppressionCellHeaderCellHeaderPayload 1PktHdrPayload 2 Payload 3PktHdrPktHdrPayload 1PktHdrPayload 2 Payload 3PktHdrPktHdrPayload 1 Payload 2 Payload 3Raj JainThe Ohio State University16Physical Media Physical Media Dependent LayersDependent LayersMultimode Fiber: 100 Mbps using 4b/5b, 155 Mbps SONET STS-3c, 155 Mbps 8b/10bSingle-mode Fiber: 155 Mbps STS-3c, 622 MbpsShielded Twisted Pair (STP): 155 Mbps 8b/10bCoax: 45 Mbps, DS3, 155 MbpsUnshielded Twisted Pair (UTP)UTP-3 (phone wire) at 25.6 Mbps, 51.84 MbpsUTP-5 (Data grade UTP) at 155 MbpsDS1, DS3, STS-3c, STM-1, E1, E3, J2, n × T1Raj JainThe Ohio State University17SummarySummaryATM Overview: History, Why and WhatProtocol Layers: AAL, ATM, Physical layers, Cell formatInterfaces: PNNI, NNI, B-ICI, DXIRaj JainThe Ohio State University18ATM : Key ReferencesATM : Key ReferencesSee http://www.cis.ohio-state.edu/~jain/atm_refs.htmG. Sackett and C. Y. Metz, “ATM and Multiprotocol Networking,” McGraw-Hill, 1997S. 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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