ObjectivesATM theory & conceptsATM cell formatProtocol stack of ATM especially AAL2 and AAL5 processing Application of ATM in a CDMA2000 SystemAt the end of this course, you will be familiar with:

Course OutlineChapter 1 OverviewChapter 2 Basic Concepts of ATMChapter 3 ATM Protocol & Service TypeChapter 4 Basic Concepts of IPOAChapter 5 ATM in CDMA2000 BSS

Why do we need a new technology?To provide a high-speed, low delay multiplexing and switching network to any type of user traffic, such as voice support, data,or video applications.

What is ATM?ATM for Telecommunications is Asynchronous Transfer Mode, (not Automatic Teller Machine!).ATM is a technology that has transport, switching, network management, and customer services built into it right from the start.In general, ATM means that traffic is carried in small, fixed-length packets called cells.A technology that integrates advantages of circuit switch and packet switch.ATM can support any type of user services, such as voice, data, or video service.

ATM Overview53byte fixed length cell= 5Bytes cell header+48Bytes payload.ATM must set up virtual connection before communication.ATM network will confer with terminal on parameter of QoS before the connection is set up.Contract5-Bytes Header48-Bytes Payload

ATM can provides both CBR and VBR transport

Connectionless & Connection-orientedConnectionless: Every packet is transferred from different routes, so the receiving order of packets doesnt possibly depend on the sending order.Connection-oriented : All packets are transferred from the same route , so the receiving order of packets depends on the sending order. Time delay is fixed.

Traditional Switch Models CharacteristicCircuit Switching Data is sent from the same route, so time delay is fixed High-speed switching Fixed ratePacket Switching Support multi-rate switching Take full advantage of bandwidth/waste of bandwidth Time delay is not fixed

ATM Switch Models CharacteristicAny users cell will not be send periodically, and bandwidth will be shared and statistically multiplexed.Many types of service can be transferred in the same time and Quality of Service is supported in an ATM network.Fixed length cell, so switch can be controlled by hardware and high-speed switching is easy to be realized.

ATMs AdvantageIntegration of various services such as voice, image, video, data and multimedia.Standardization of network structures and components. This results in cost savings for network providers.Transmission that is independent of the medium used PDH, SDH, SONET and other media can be used to transport ATM cells.ATM is scaleable, i.e. the bandwidth can be adapted extremely flexibly to meet user requirements.Guaranteed transmission quality to match the service required by the user (quality of service, QoS).

ATMs ApplicationIn Switching:Traditional Exchange is evolving into Broadband Exchange by ATMs applicationIn Transmission:ATM virtual path exchange node and ATM Add/Drop MultiplexerIn Internet:ATM router applied in IP Switching, Multi-Protocol Label Switching

Course OutlineChapter 1 OverviewChapter 2 Basic Concepts of ATMChapter 3 ATM Protocol & Service TypeChapter 4 Basic Concepts of IPOAChapter 5 ATM in CDMA2000 BSS

ATM Network ModelUNIUNIUNIPNNIPNNINNINNINNINNINNINNINNIICIOther NetworkNNINetwork Node InterfaceUNIUser Node InterfaceICIInter-carrier InterfacePNNIPrivate Network Node Interface

ATM Cell

ATM CellGFC ( Generic Flow Control): It is intended for control of a possible bus system at the user interface and is not used at the moment.VPI ( Virtual Path Identifier): The VPI contains the second part of the addressing instructions and is of higher priority than the VCI. VCI ( Virtual Channel Identifier): VCI in each case indicates a path section between switching centers or between the switching center and the subscriber.PTI ( Payload Type Identifier): Indicates the type of data in the information field.CLP ( Cell Loss Priority): Determines whether a cell can be preferentially deleted or not in the case of a transmission bottleneck.HEC ( Header Error Control): Provided in order to control and, to some extent, correct errors in the header data that may occur. The HEC is used to synchronize the receiver to the start of the cell.

VP and VCWhy two fields?think VPI as a bundle of virtual channels. (256 VPI on one link)the individual virtual channels have unique VCIs. The VCI values may be reused in each virtual path.

Port 1 VPI=2 VCI=37 VPI=3 VCI=39NNIUNIUNIATM Cell SwitchingATM SwitchPort VPI VCI 1 2 37 2 1 51 Port 2Port 1ATM SwitchPort VPI VCI 1 1 51 2 3 39 Port 2ATM TerminalUser BUser AATM Network Node Cell and users data change each otherVPI=1 VCI=51ATM Network Node ATM TerminalCell and users data change each other

ATM Connections

ATM Virtual ConnectionUNI cell VPI =1 VCI =1UNI cell VPI =20 VCI =30NNI cell VPI =26 VCI =44NNI cell VPI =6 VCI =44NNI cell VPI =2 VCI =44123

123132231ATM Virtual Connection

ABIn order to exchange cells between A and B, several tables must be set up in network node where the cells passed. After these tables have been set up, all the cells will be transferred along this route. This route is called Virtual Connection.

Signaling In ATMPermanent Virtual Channel (PVC): The connections are analogous to leased lines that are switched between certain users. A change can only be made by the network provider. This type of ATM network often forms the initial stage in the introduction of this technology.

Switch Virtual Channel (SVC): Users connected to this type of network can set up a connection to the user of their own choice by means of signaling procedures. This can be compared with the process of dialing a telephone number.

Types of ATM Virtual ConnectionAccording to the switching mode, ATM Virtual Connection can be classified :VPC (Virtual Path Connection)VCC (Virtual Channel Connection)According to connection establishment, ATM Virtual Connection can be classified:SVC(Switching Virtual Connection)PVC(Permanent Virtual Connection)

VPC and VCCUNI cellATM terminal ACATM network node GUNI cellNNI cellNNI cellVC switchingVCCVPCVCCUNI cellUNI cellBDFor example: When E receives cells from A or B, which would be transferred to C or D, the VPI of these cells would be set to uniform value in E. These cells would be received by G and switched to F by VP switching. Then the cells will be delivered to C or D at F. It means that VPC has been set up between E and F, while VCC has been set up among A, B, C and D.EFVP switchingVC switching

Course OutlineChapter 1 OverviewChapter 2 Basic Concepts of ATMChapter 3 ATM Protocol & Service TypeChapter 4 Basic Concepts of IPOAChapter 5 ATM in CDMA2000 BSS

Features of ATM Connection oriented Fast packet switching Statistical multiplexer Supports voice, data and video service Provides QoS

ATM Protocol Structure ModelUSER SAALATM LayerPhysical Layer AALUSERService and signaling of userInformation of user and cell conversionCell exchange and multiplexing or demultiplexingFrame structure physical mediumImpartiblemanagement of all layerIndependent management of every layer Call connection and ControlUser informationFlow Control and Error RecoveryInterface ManagementLayer ManagementControl interfaceUser interface

Three Communications PlanesThe user plane transports the user data for an application. It uses the physical, ATM and ATM adaptation layers to do this.The control plane takes care of establishing, maintaining and clearing down user connections in the user plane. The key word here is signaling.The management plane includes layer management and plane management. Layer management monitors and coordinates the individual layer tasks. Plane management handles monitoring and coordination tasks in the network.

ATM Sublayer ModelATM Protocol Stack ModelOSI Reference Model UserPMDTCPHYATMAALCSSARInterface management7 Application 6 Presentation5 Session 4 Transport 3 Network 2 Data link 1 Physical

Two sublayers:

Transmission Convergence Sublayer (TC)transmission frame generation/recoveryProcessing HECcell delimitingtransmission frame adaptation

Physical Medium Dependent Sublayer (PMD)Link coding Network physical mediumFunction of ATM Physical LayerAALATMPHY

Cell switch Quality of Service Processing the cell header Types of payload Multiplexing /Demultiplexing of different connection cellFunction of ATM LayerAALATMPHY

Support services for user Segment and reassemble Complete the change between User-PDU and ATM payloadFunction of AAL layerAALATMPHY

Function of ATM AAL OverviewFunction of ATM AAL:Provide a high-speed, low delay multiplexing and switching network to support any type of user service, such as voice, data,or video applications.ATM PayloadConstantBit RateData BurstsVariable Bit RateATM Cell MultiplexingAAL SDU

Types of AALIn order to support different types of user services, there are five types of AAL.

In Huaweis BSS, voice is transferred over AAL2 and rest signals are transferred over AAL5.Service typeABCDBit rateconstantvariablevariablevariableReal time YESYESNONOConnection modeConnection orientedconnectionlessAALAAL1AAL2AAL3/4AAL5

Logic Structure of AAL LayerCS sublayerProvide service to upper layer at AAL-SAP.

The concrete function is depending on the service type. CS can be further divided into SSCS and CPCS.

SAR sublayer: Chop CCS-PDU into ATM payload with size of 48 bytes or assemble ATM payload into CPCS-PDU.SSCSCPCSSARSSCS-PDUCPCS-PDUSAR-PDUAAL-PDUCPCS-SDUSAR-SDUATM-SDUAAL layerATM layer

AAL2 StructureAAL2 contains two sub-layer, CPS and SSCS.The function of SAR is performed by CPS, SAR sub-layer is nullFor AAL2CPS is changeless no matter which type of service is. But it is different for SSCS. Sometimes SSCS maybe null.SSCSCPCSSSCS-PDUCPS-PDUAAL-PDUCPS-SDUATM-SDUAAL layerATM layer

AAL2 ProcessAAL LayerSSCS-PDU HeaderSSCS-PDU TailCPS-PacketCPS-PacketSSCS-PDU 45Bit MaxCPS-PacketCCPS-Packet1#3#2#1#3#2#CPS-PDU Payload 47 BitCPS-PDUSSCSCPSSNATM LayerOSF PSTF CPS-PacketPS-PacketPADATM-Header

AAL5 StructureAAL5 contains two sub-layers, CS and SAR sublayer.CS sublayer is further divided into SSCS and CPCS.In order to enhance the effect of AAL3/4, CPCS and SAR are appropriately simplified. AAL5 doesnt support multi-user multiplexing mode.SSCSCPCSSARSSCS-PDUCPCS-PDUSAR-PDUAAL-PDUCPCS-SDUSAR-SDUATM-SDUAAL layerATM layer

AAL5 ProcessAAL LayerCPCSATM LayerUU CPI Length CRC 8181161321CPS-PDU N48 BytesPAD047BitsSAR-PDU #1SAR-PDU #2SAR-PDU #3SAR-PDU #4ATM-SDU #1ATM-SDU #2ATM-SDU #3ATM-SDU #4Cell #1Cell #2Cell #3Cell #4ATM Payload:ATM Header (AUU=0):ATM Header (AUU=1)SAR

Service Types of ATM layer CBR (Constant bit rate) VBR-RT (Variable bit rate-real time) VBR-NRT (VBR-non real time) UBR (Unspecified bit rate) ABR (Available bit rate)

ATM Service Categories

CBR ServiceQoSTraffic parameterlowhighToleranceCell delay and cell delay variationCell lossPCRVoice and video

VBR ServiceQoSTraffic parameterLOWHIGHToleranceCell lose (NRT)Cell lose (RT)PCRSCRMBSVoice and video

UBR ServiceQoSTraffic parameterlowhighNo QoSToleranceCell loseCell relay variation

ABR ServiceLANOverheadNo cell overheadUses congestion feedback instead5 Byte Header48 Byte PayloadQoSTraffic parameterlowhighPCRMCRToleranceCell lossCell delay variation

ATM Service Categories and their Parameters

ATM Service Categories and Applications

Communication ContractATM network Communication ContractService TypesParameter of FlowParameter of QoS

Service type in CDMA2000 BSS SystemVariable bit rate real time(VBR-RT), such as voice service in CDMA2000 BSS System. It is realized by AAL2.

Variable bit rate non real time (VBR-NRT), such as signaling and other service in CDMA2000 BSS System. It is realized by AAL5.

Course OutlineChapter 1 OverviewChapter 2 Basic Concepts of ATMChapter 3 ATM Protocol & Service TypeChapter 4 Basic Concepts of IPOAChapter 5 ATM in CDMA2000 BSS

IPOA Protocal StackATM network Physical layerIP address is mapped to PVC or SVCUser applicationATMAALIPTCP/UDPATMAALIPTCP/UDPIP packet is transferred to ATM PayloadUser application

TCP/IP ProcessApp DataTCP HeaderTCP headerApp DataIP HeaderIP HeaderTCP HeaderApp DataLLCSAR-SDU#1SAR-SDU#2SAR-SDU#3SAR-PDU#4SAR-PDU#5TCPIPSNAP/LLCAAL5CSSARATMPHYCell header will be added to SAR-PDU, whose VPI and VCI depends on the map table of IP address to PVC/SVC. Then ,the cells will be sent to Physical Layer. Perform the transmission of ATM cells via physical media.LLCIP HeaderTCP HeaderApp DataPADCPCS-PDU Tail

INARP in IPOANetwork ModelSVC modeATM NetworkARP ServerEthernetWANRouter

INARP in IPOANetwork Model PVC modeATM NetworkEthernetWANRouter

INARP in IPOAPVC ModeATM NetworkPVC Any IPOA terminal that wants to communicate with other terminal must know the destination IP address. But how to know the IP address? PVC connecting the source and destination terminals should be set up first. For example: Terminal A must set up a PVC to B in order to know the IP address of B.

ARP in IPOAPVC ModeTerminal A will send InvATMARP information to request remote IPOA client s (such as computer B) IP address. So does computer B.ATM NetworkPVCInvATMARPInvATMARP

ARP in IPOAPVC ModeThereby, A and B establish the map table of IP address to PVC. Similarly, all the IPs of the computers that answered the InvATMARP will be set to the map table. ATM NetworkPVCACKACK

ARP in IPOAPVC Mode For example: A will transfer a IP packet to B, and the IP packet will be changed to AAL-PDUs first. When ATM layer receives AAL-PDU,it can find the PVC by map table and set VPI/VCI of ATM cell. Thereby, cells could be transferred to B by ATM network.ATM NetworkPVCATM cell streamATM cell stream

Course OutlineChapter 1 OverviewChapter 2 Basic Concepts of ATMChapter 3 ATM Protocol & Service TypeChapter 4 Basic Concepts of IPOAChapter 5 ATM in CDMA2000 BSS

ATM in CDMA2000 BSS systemLarge Capacity Configuration Resource Management & Packet Processing Subrack (CRPS) Integrated Processing Subrack (CIPS)BTS baseband frame service/ signal-in-band AAL2 maintenance / signal-out-band AAL5 Abis interface: signal-in-band/serviceAAL2 signal-out-band /maintenanceAAL5 IPOAIf Abis interface is connected with several E1 cables, IMA mode will be adopted to transfer ATM cells. BSC inside VoiceAAL2signal/data service:AAL5 maintenanceAAL5 IPOA Connected to MSC Data Service Processing Subrack (CPMS)Connected to PDSN Optic fiberOptic fiberEthernet cablecBSCSwitch SubrackGPS/GlonassreceiverOptic fiberIntegrated Management Subrack (BAM)

ATM in CDMA2000 BSS SystemSmall Capacity Configurationseveral E1 cablesBTS baseband frame service/ signal-in-band AAL2 maintenance / signal-out-band AAL5 Abis interface: signal-in-band/serviceAAL2 signal-out-band /maintenanceAAL5 IPOAIf Abis interface is connected with several E1 cables, IMA mode will be adopted to transfer ATM cells. BSC inside VoiceAAL2signal/data service:AAL5 maintenanceAAL5 IPOAConnected to MSCResource & Packet SubrackIntegrated Management Subrack (BAM)Connected to PDSN cBSCGPS/Glonass Receiverseveral E1 cables or Optic fiberIntegrated Processing SubrackEthernet cableLAN

IMA ModePHYIMA GroupPHYPHYPHYIMA GroupPHYPHYPhysical Link #1Physical Link #0Physical Link #2Virtual ATM Link If Abis interface is connected with several E1 cables, IMA mode will be adopted to transfer ATM cells. In this way, cells of high speed ATM link could be transferred on several low speed physical links. ATM LayerATM Layer

SummaryATM BasicsATM switching is cell switching,it has advantage of circuit switch and packet switch, connection oriented .ATM cell:53byte fixed length cell= 5Bytes cell header+48Bytes payloadATM switching ATM switching has two types:VP and VC switch. As a rule: only VPI has been changed in VP switch,Both VCI and VPI have been changed in VC switch. VPI and VCI is only of effect between the two ATM physical nodes.

QuestionsState ATM application in CDMA2000 BSS system?What is the difference between SVC and PVC?What is the difference between VP switch and VC switch?

ATM (Asynchronous Transfer Mode) is a high speed packet switching technology. It supports any kind of service.

VPI:Virtual Path IdentifierVCI:Virtual Channel IdentifierATM is a circuit switched procedureThe connection through ATM network is called as virtual, since it does not exist physically, but it is present only in the form of routing tables in the switching center. Traditional Switch Module:Circuit switching, data is sent on the same route. Here statistical multiplexing means, TS are not fixed. Information is sent over several TS may these are adjacent or may be different. GFC ( Generic Flow Control): Supports the configuration of the subscriber equipment. It is intended for the control of a possible bus system at the user interface.VPI ( Virtual Path Identifier): VPI contains the second part of the addressing instructions and is of higher priority than the VCI. This allows the rapid direction of the cells through the network. ATM cross-connects the cell stream in various directions based on VPI. The VPI and VCI are assigned by the switching centers when the call is being established.VCI ( Virtual Channel Identifier): This field contains part of the addressing instructions. All cells belonging to the same virtual channel have the same VCI. VCI indicates a path section between switching centers or between switching center and subscriber. PTI ( Payload Type Identifier): A distinction is made between network and user information.CLP ( Cell Loss Priority):The contents of this field determines whether a cell can be preferentially deleted or not during congestion. CLP=0 Lower priorityCLP=1 Higher priorityHEC ( Header Error Control): The HEC is used to synchronize the receiver to the start of the cell. CRC code is also sent over it (x8+x2+x+1)

There are cells for transmitting the signaling information and OAM cells. VCVirtual Connection 37 PVC: Permanent Virtual Channel, A PVC in the usual meaning is a VC that is not signaled by the end points. Both of the endpoint (user) VC values are manually provisioned. The link-by-link route through the network is also manually provisioned. If any equipment fails, the PVC is down, unless the underlying physical network (SONET, for example) can re-route below ATM. SVC: A SVC is established by UNI signaling methods. So an SVC is a request oriented connection initiated by the user. If some equipment in the path fails, the SVC is broken and would have to be reconnected. SSCS:Service Special Convergence Sublayer CPCS:Common Part Convergence Sublayer CS:Convergence Sublayer SAR:Segmentation And Reassembly AAL:ATM Adaptation Layer PHY:Phsical Layer TC:Transmission Convergence Sublayer PMD:Physical Medium Dependent Sublayer HEC: Header Error Control AAL-SAPAAL service access pointATM-SAPATM service access pointAAL-SDU:AAL-Service Data UnitSSCS-PDU:SSCS-Protocol Data UnitCPCS-PDU:CPCS-Protocol Data UnitSAR-PDU: Segmentation And Reassembly Protocol Data UnitATM-SDU:ATM-Service Data Unit

AAL is divided into two sub-layers:a: Segmentation & Reassembly (SAR) is used to segment the PDUs of the higher layer into blocks and vise versa. b: is further subdivided1: Common part CS (CPCS), deals with packet forming and error correction2: Service Specific CS (SSCS), provides the specific class of AAL user function.Each AAL has a specific SAR and CPCS and several SSCS sub-layers.

Intended for the bandwidth efficient transfer of low-bit rate, short packet traffic that has low delay requirement. In fact AAL2 adds a third level of multiplexing to the VP/VC hierarchy of ATM, so that two or more low-bit rate users can share the same ATM connection.

CPCS, provides non assured operation. CPCS can multiplex SDUs from multiple SSCS users. Notes:Max length of SSCS-PDU has two choice:45Bytes and 64Bytes. SSCS: Service Specific Convergence SublayerCPS:Common Part SublayerSDU:Service Data UnitPDU:Protocol Data UnitCPS-PH:Common Part Sublayer-Packet Header CPS-PP:Common Part Sublayer-Packet Payload STF:Start FieldCID:Channel Identifier 8BitsLI:Length Indicator 6BitsUUI:User to User Indicaton 5BitsHEC:Header Error Control 5BitsOSF:Offset Field CPS-Packet6BitsSN:Sequence Number CPS-PDU1BitsP: Parity 1BitsPAD: Pad data047Bits

Provides efficient alternative to AAL3/AAL4In this layer, CPCS can attach 0-47 bytes of padding (PAD) and 8-byte trailer to produce a CPCS PDU. The maximum CPCS-PDU is 65,5 35bytes.

Unlike AAL3/4, AAL5 can have only one packet at a time in a VC because the cells from different packets cant be intermixed.

1Keep CPCS-SDU2Keep CPCS-SDU3Error check and manage4Interrupt5Pad6Congestion information manage7Lose priority information manage

Attention :Slide only shows CPCS and SAR of AAL5.Because SSCS must be modified according to different traffic,it is not shown in slide.UU: User to User Indication 8BitsCPI: Common Part Indication 8BitsLength: Length of CPCS-PDU 16BitsCRC: Cyclic Redundancy Check 32Bits PTI: Payload Type Indicator 3BitsAUU: ATM User to User Indication 1Bits

PCR: Peck Cell RatePCR: Peck Cell RateSCR: Sustainable Cell RateMBS: Maintainable Cell Rate IP Over ATM This page reference page :AAL5 Process.ReferenceRFC1483SNAP: Sub-network Access Protocol LLC: Low Layer Compatability In order to realize INARP in IPOA, all computers in ATM network are see as ATM terminal, such as: ARP server, router. All IP packets are changed into ATM payload and all IP address of computer are changed into ATM address or ATM PVC.INARP: Inverse Address Resolution Protocol IMAInverted Multiplex Adaptation