VOIP技术介绍

VOIP技术介绍方案咨询部吴涛[e-mail]议题VOIP技术概述VOIP业务方案主要的几个协议层次CCBCSCMCSECCBCSCMCSEServiceControlCallControlMediaControlBearerControlServicesSDPH.245SIP,H.323SS7,ISDNOSP,H.255AnxGINAP,SIPXML,CPLMGCP,MEGACO/H.248RTPFRF.11Parlay,JAIN,other什么是H.323标准H.323是在无QoS保证的LAN上进行多媒体通信系统标准。H.323是于1996年3月27日到6月7日，ITU－T第16组在日内瓦会议上正式提出的，最初是叫作“工作于不保证业务质量的LAN上的多媒体通信终端系统”。1997年底通过了H.323V2，改名为“基于包交换网络的多媒体通信终端系统”。1998年2月正式通过时又去掉了版本2的V2称呼，就叫作H.323。1999年5月ITU－T又提出了H.323的V3版本,目前正在审定H.323标准族VIDIOAPPLICATIONSAUDIOAPPLICATIONSTERMINALCONTROLANDMANAGEMENTlayer5-7H.261G711/G726H225callsignaling(RTP)H.263G723/G723.1H245controlchannel(RTCP)G728G729/G729Alayer2layer1internetprotocal(IP)physicallayer(IEEE802.3)reliabletransport(RTP)layer3-4H.323realtimeprotocal(RTP)unreliabletransport(UDP)主要组件定义了四种主要组件：终端(TM)网关(GW)关守(GK)媒体控制单元（MCU）H.323网络构成InternetPSTNIntranetH.323TerminalH.323TerminalGatekeeperMCUGatewayH.320Terminal(ISDN)H.324Terminal(POTS)SpeechOnlyH.323TerminalH.323WithoutRAS-CallSet-upMedia(UDP)RTPStreamRTCPStreamH.323GatewayH.245(TCP)OpenLogicalChannelH.225(TCP)SetupConnectOpenLogicalChannelAcknowledgeCapabilitiesExchangeRTPStreamH.323GatewayAssumesEndpointsknoweachother’sIPaddressesSignalingBearerorMediaQ.931derivedCall-SetupRTP/RTCPaddressnegotiationVVIPQoSNetworkPSTN/PrivateVoicePSTN/PrivateVoicePOTS/PSTNCallSet-up:Ringing,Answer...H.323WithRASGatekeeperGatewayAGatewayBIPQoSNetworkH.225(Q.931)CallSetup(TCP)RTP(UDP)H.245CallControl(TCP)VVIntra-ZoneCallSet-upGK11)TerminalAdialsthephonenumber408-667-1111forTerminalB2)GWAsendsGK1anARQ,askingpermissiontocallTerminalB3)GK1doesalook-upandfindsTerminalBregistered;returnsanACFwiththeIPaddressofGWB4)GWAsendsaQ.931Call-SetuptoGWBwithTerminalB’sphonenumber5)GWBsendsGK1anARQ,askingpermissiontoanswerGWA’scall6)GK1returnsanACFwiththeIPaddressofGWA7)GWBsetsupaPOTScalltoTerminalBat408-667-11118)WhenTerminalBanswers,GWBsendsQ.931ConnecttoGWATerminalA415-557-1111GWAGWBTerminalB408-667-111123456817Inter-ZoneCallSet-up1)TerminalAdialsthephonenumber408-667-1111forTerminalB2)GWAsendsGK1anARQ,askingpermissiontocallTerminalB3)GK1doesalook-upanddoesNOTfindTerminalBregistered;GK1doesaprefixlook-upandfindsamatchwithGK2;GK1sendsanLRQtoGK24)GK2doesalook-upandfindsTerminalBregistered;returnsanLCFwiththeIPaddressofGWB5)GK1returnsanACFwiththeIPaddressofGWB6)GWAsendsaQ.931Call-SetuptoGWBwithTerminalB’sphonenumber7)GWBsendsGK2anARQ,askingpermissiontoanswerGWA’scall8)GK2returnsanACFwiththeIPaddressofGWA9)GWBsetsupaPOTScalltoTerminalBat408-667-111110)WhenTerminalBanswers,GWBsendsQ.931ConnecttoGWAGK1GWAGWB61019257834GK2TerminalA415-557-1111TerminalB408-667-1111Inter-ZoneCallSet-up:DirectoryGatekeeper1)TerminalAdialsthephonenumber408-667-1111forTerminalB2)GWAsendsGK1anARQ,askingpermissiontocallTerminalB3)GK1doesalook-upanddoesNOTfindTerminalBregistered;GK1doesaprefixlook-upandfindsawildcardmatchwithDir-GK;GK1sendsLRQtoDir-GK4)Dir-GKdoesaprefixlook-upandfindsGK2;ForwardstheLRQtoGK25-11)Sameassteps4-10inpreviousscenario711110268935GWBGWAGK1GK2Dir-GK4TerminalA415-557-1111TerminalB408-667-1111IP电话应用IP电话网关IP电话网关PSTNISDNGSMCDMAPSTNISDNGSMCDMAIP电话网的管理层SIP协议SIP系统组成用户代理用户代理客户机（UAC）用户代理服务器（UAS）网络服务器代理服务器（proxy）重定位服务器（redirect）注册服务器(Registrar)SIP的基本模块RedirectServerLocationServerRegistrarServerUserAgentProxyServerGatewayPSTNSIPComponentsProxyServerSIP的总体框架SipproxySipproxySipUserSipUserRequestResponse非sip协议SipredirectserverSiplocalserverSipproxy122437109865USERAGENTPingtelxpressaCisco7960SIPIPPhonePCwithsoftphoneapplicationKomodoATA182/186SIPsyntaxexampleINVITEsip:[e-mail]/2.0Via:SIP/2.0/UDPstation1.work.comFrom:Danielsip:[e-mail]:Bosssip:[e-mail]-ID:[e-mail]:1INVITESubject:VacationContent-Length:156Content-Type:application/sdpSIP/2.0180RingingVia:SIP/2.0/UDPstation1.work.comFrom:Danielsip:[e-mail]:Bosssip:[e-mail]-ID:[e-mail]:1INVITEContent-Length:0SIP/2.0200OKACKConversation基于SIP的VOIP网络BY-PASSDomainControl基于SIP的VOIP网络基于SIP的VOIP网络基于SIP的VOIP网络Softswitch&NGN传统交换网STPSTPSTPSTPSP(SSP)SP(SSP)SP(SSP)SP(SSP)SP(SCP)SP(SCP)SignallingNetworkTransportNetworkExchangeExchangeExchangeExchangeWhatisa“Softswitch”?ASoftswitchisasoftware-basedentitythatprovidescallcontrolfunctionality长远目标替换电路交换网络（本地交换和长途交换）实现步骤实现长途交换智能网的扩展，实现多种新业务宽带网络电话和PSTN并存替换本地市话业务ArchitectureofsoftswitchPSTNPSTNSS7SS7SCPSCPVOIPTerminalInternetISUPTrunksISUPTrunksRTPRTPMGCPMGCPSIP+/SIP-TSoftswitchSoftswitchConvergedApplicationServer交换机交换机JAIN/parley/SIPSCE(IN)TrunkGWTrunkGWServicesMarketDemandInternetCallDiversionEnhancedServicesBasicLocalServicesVoIP/VoATMTrunkingEnhancedMobileServices199920002001200220032004ServiceComplexitySource:TheYankeeGroupVOIP应用阶段一长途交换模式PSTNTrunkingGatewaysIPBACKBONETrunkingGatewaysClass-5Hello?HiThere!Class-5Class-4SOFTSWITCHSS7Network应用实例（美国&网通）Level3QwestNTT网通注：技术已经成熟，但必须增添新业务才能更有吸引力.在2000年，整个SoftSwitch方案主要是围绕ATM网络来建设的，基于IP的方案很少，主要是考虑到QOS的问题，这个问题至今存在。阶段二同智能网的结合新业务SoftSwitchSTPSCPSS7SingalingGWTrunkingGWClass5PSTNSS7ININAP/M