Raj Jain1ATM Networks:ATM Networks:An OverviewAn OverviewRaj JainProfessor of Computer and Information SciencesThe Ohio State UniversityColumbus, OH 43210-1277These slides are available athttp://www.cis.ohio-state.edu/~jain/cis777-99Raj Jain2q ATM vs Phone Networks and Data Networksq ATM Protocol Layersq Cell Header Format, AALsq Physical Mediaq Traffic Management: ABR, UBR, GFROverviewOverviewRaj Jain3ATMATMq ATM Net = Data Net + Phone Netq Combination of Internet method ofcommunication (packet switching) and phonecompanies’ method (circuit switching)ATMRaj Jain4ATM vs Phone NetworksATM vs Phone Networksq Current phone networks are synchronous (periodic).ATM = Asynchronous Transfer Modeq Phone networks use circuit switching.ATM networks use “Packet” Switchingq In phone networks, all rates are multiple of 8 kbps.With ATM service, you can get any rate.You can vary your rate with time.q With current phone networks, all high speed circuitsare manually setup. ATM allows dialing any speed.125 µsRaj Jain5ATM vs Data NetworksATM vs Data Networksq Signaling: Internet Protocol (IP) is connectionless.You cannot reserve bandwidth in advance.ATM is connection-oriented.You declare your needs before using the network.q PNNI: Path based on quality of service (QoS)q Switching: In IP, each packet is addressed andprocessed individually.q Traffic Management: Loss based in IP.ATM has 1996 traffic management technology.Required for high-speed and variable demands.q Cells: Fixed size or small size is not importantRaj Jain6Old House vs New HouseOld House vs New Houseq New needs:Solution 1: Fix the old house (cheaper initially)Solution 2: Buy a new house (pays off over a long run)Raj Jain7PrivateNNIPrivateUNIATM InterfacesATM InterfacesComputerPrivateSwitchPublicSwitchRouterDigitalServiceUnitDXIB-ICIPublicUNIPublicNNIPrivateUNIPrivateSwitchPublicSwitchCarriersPublicSwitchCarrierComputerRaj Jain8ATM InterfacesATM Interfacesq User to Network Interface (UNI):Public UNI, Private UNIq Network to Node Interface (NNI):m Private NNI (P-NNI)m Public NNI =Inter-Switching System Interface (ISSI)Intra-LATA ISSI (Regional Bell Operating Co)m Inter-LATA ISSI (Inter-exchange Carriers)⇒ Broadband Inter-Carrier Interface (B-ICI)q Data Exchange Interface (DXI)Between routers and ATM Digital Service Units (DSU)Raj Jain9ATM LayerATM Adaptation LayerPhysicalLayerATM LayerPhysicalLayerATM LayerATM Adaptation LayerPhysicalLayerEnd System End SystemSwitchProtocol LayersProtocol LayersRaj Jain10Protocol LayersProtocol Layersq The ATM Adaptation Layerm How to break messages to cellsq The ATM Layerm Transmission/Switching/Receptionm Congestion Control/Buffer managementm Cell header generation/removal atsource/destinationm Cell address translationm Sequential deliveryRaj Jain11Cell Header FormatCell Header Formatq GFC = Generic Flow Controlm (Was used in UNI but not in NNI)q VPI/VCI = 0/0 ⇒ Idle cell; 0/n ⇒ Signalingq HEC: 1 + x + x2 + x8VCI PTIHeader Error Check (HEC)VCIVPI VCIGFC/VPI VPICLPPayloadRaj Jain12Path vs ChannelsPath vs Channelsq 24/28-bit connection identifierFirst 8/12 bits: Virtual Path,Last 16 bits: Virtual Circuitq VP service allows new VC's w/o orders to carriersVC1VC2VC3VC1VC2VC3VC1VC2VC3VP1VP2VP3LinkRaj Jain13VP/VC Assignment/UseVP/VC Assignment/UseSwitch33 56Video Data37 34VoiceData213453556657661122Port1/373/345/332/56VPI/VCIIn1/352/564/654/76VPI/VCI3456PortOutRaj Jain14Original Classes ofOriginal Classes ofTrafficTrafficClass 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 Jain15AAL 5AAL 5q Designed for data trafficq Less overhead bits than AAL 3/4⇒ Simple and Efficient AAL (SEAL)q No per cell length field, No per cell CRCPADUserPayloadLength CRC-32Control4220-64kB10PTI bit indicates last cell0-47Raj Jain16AAL2AAL2q Ideal for low bit rate voiceq Variable/constant rate voiceq Multiple users per VCq Compression and Silence suppressionq Idle channel suppressionCellHeaderCellHeaderPayload 1PktHdrPayload 2 Payload 3PktHdrPktHdrPayload 1PktHdrPayload 2 Payload 3PktHdrPktHdrPayload 1 Payload 2 Payload 3Raj Jain17Physical MediaPhysical Mediaq Multimode Fiber: 100 Mbps using 4b/5b,155 Mbps SONET STS-3c, 155 Mbps 8b/10bq Single-mode Fiber: 155 Mbps STS-3c, 622 Mbpsq Plastic Optical Fiber: 155 Mbpsq Shielded Twisted Pair (STP): 155 Mbps 8b/10bq Coax: 45 Mbps, DS3, 155 Mbpsq Unshielded Twisted Pair (UTP)m UTP-3 (phone wire) at 25.6, 51.84, 155 Mbpsm UTP-5 (Data grade UTP) at 155 Mbpsq DS1, DS3, STS-3c, STM-1, E1, E3, J2, n × T1Raj Jain18SummarySummaryq ATM Overview: History, Why and Whatq Protocol Layers: AAL, ATM, Physical layers, Cellformatq Interfaces: PNNI, NNI, B-ICI, DXIq ABR, CBR, VBR, UBR, GFRRaj Jain19ATM : Key ReferencesATM : Key Referencesq G. Sackett and C. Y. Metz, “ATM and MultiprotocolNetworking,” McGraw-Hill, 1997 (Technical).q K. Siu and R. Jain, "A Brief Overview of ATM:Protocol Layers, LAN Emulation, and TrafficManagement," Computer Communications Review(ACM SIGCOMM), April 1995, http://www.cis.ohio-state.edu/~jain/q ATM Forum specs are available atftp://ftp.atmforum.com/pub/approved-specs/q For additional references, see
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