VOIP培训和信令类型介绍

1、VOIP培训和信令类型介绍2022/7/181OUTLINE VOIP简介VOIP协议族媒体流传输信令H323SIPMGCP声音处理NGNVOIP应用中的NAT问题22022/7/18What is itVoIP Stands for Voice over IPV2oIP Stands for Voice & Video over IP32022/7/18采样42022/7/18编码52022/7/18传送62022/7/18寻址 号码/别名和IP地址的对应72022/7/18TerminalPacket BasedNetworksGatekeeperGatewayCircuit Switch

2、edNetworks呼叫建立和控制82022/7/18PSTNGatekeeperTerminalGatewayH.245 messages over call control channelH.225/Q.931 (optional)H.225/Q.931 (optional)H.245 messages (optional)OUTLINEVOIP简介 VOIP协议族媒体流传输信令H323SIPMGCP声音处理NGNVOIP应用中的NAT问题92022/7/18VOIP协议族102022/7/18RTCPRTPIPMGCPCall Control and SignalingSignaling

3、 and Gateway ControlMediaTCPRASUDPSIPAudio/VideoRTSPOUTLINEVOIP简介VOIP协议族媒体流传输信令H323SIPMGCP声音处理112022/7/18实时媒体流实时流 在一个给定的时间必须可用或就绪的数据流和普通数据的区别：实时分组交换网上传输实时流的问题：时延抖动错序丢失122022/7/18时延132022/7/18固定延迟的构成传播每公里6毫秒串行化 处理编码/压缩/解压缩/解码分组化142022/7/18Processing DelayPropagation DelaySerialization DelayBuffer to

4、Serial Link变化时延构成排队延迟消抖缓冲器可变分组规模152022/7/18DejitterBufferQueuing DelayQueuing DelayQueuing Delay丢失162022/7/18解决的方法172022/7/18RTP/RTCP RFC1889/1890182022/7/18RTP/RTCP RFC1889/1890时间戳：抖动序列号：错序、丢失通过JITTER BUFFER实现192022/7/18OUTLINEVOIP简介VOIP协议族媒体流传输信令H323SIPMGCP声音处理NGNVOIP应用中的NAT问题202022/7/18信令用户的接入呼叫的

5、建立和控制H323 ITU-TSIP/MGCP - IETF Megaco/H248 IETF/ITU-T212022/7/18IPMGCPCall Control and SignalingSignaling and Gateway ControlTCPRASUDPSIPH323框架Call establishment and teardown.Audio visual or multimedia conferencing222022/7/18TerminalGatewayPacket BasedNetworksMultipoint Control UnitGatekeeperCircuit

6、 SwitchedNetworksH323框架232022/7/18H323终端H.323 terminals are client endpoints that must support:H.225 call control signaling.H.245 control channel signaling.RTP/RTCP protocols for media packets.Audio codecs.Video codecs support is optional242022/7/18H323 GATEWAYA gateway provides translation:For exam

7、ple, a gateway can provide translation between entities in a packet switched network (example, IP network) and circuit switched network (example, PSTN network).Gateways can also provide transmission formats translation, communication procedures translation, H.323 and non-H.323 endpoints translations

8、 or codec translation252022/7/18H323 GateKeeperGatekeepers provide these functions:Address translation.Bandwidth control.Zone management.Admission control.Call control signaling (optional).Call authorization (optional).Bandwidth management (optional).Call management (optional).Gatekeepers are option

9、al but if present in a H.323 system, all H.323 endpoints must register with the gatekeeper and receive permission before making a call.262022/7/18H.323 Multipoint Control UnitMCU provide support for conferences of three or more endpoints.An MCU consist of:Multipoint Controller (MC) provides control

10、functions.Multipoint Processor (MP) receives and processes audio, video and/or data streams.272022/7/18H323协议栈282022/7/18H323协议栈Call Control and Signaling - Capabilities advertisement, media channel establishment, and conference control.Q.931 - call signaling and call setup.RAS - registration and ot

11、her admission control with a gatekeeper.292022/7/18Call Control and SignalingData/FaxMediaIPUDPRTPAudioCodecG.711G.723G.729VideoCodecH.261H.263RTCPH.225Q.931H.225RASH.245T.120T.38TCPTCPUDPTCPData/Fax Data conferencing. Fax.Media Video codecs. Audio codecs.RTP/RTCP Media.H323实体和信令302022/7/18H.245 A p

12、rotocol for capabilities advertisement, media channel establishment and conference control.H.225 - Call Control.- Q.931 A protocol for call control and call setup.- RAS Registration, admission and status protocol used for communicating between an H.323 endpoint and a gatekeeper.PSTNGatekeeperTermina

13、lGatewayH.245 messages over call control channelH.225/Q.931 (optional)H.225/Q.931 (optional)H.245 messages (optional)H.245 messages (optional)Process for Establishing CommunicationEstablishing communication using H.323 may occurs in five steps:Call setup.Initial communication and capabilities exchan

14、ge.Audio/video communication establishment.Call services.Call termination.312022/7/18简化的H.323 Call SetupBoth endpoints have previously registered with the gatekeeper.Terminal A initiate the call to the gatekeeper. (RAS messages are exchanged).The gatekeeper provides information for Terminal A to con

15、tact Terminal B.Terminal A sends a SETUP message to Terminal B.Terminal B responds with a Call Proceeding message and also contacts the gatekeeper for permission.Terminal B sends a Alerting and Connect message.Terminal B and A exchange H.245 messages to determine master slave, terminal capabilities,

16、 and open logical channels.The two terminals establish RTP media paths.322022/7/18Terminal AGatekeeperTerminal BRAS messagesCall Signaling Messages1. ARQ2. ACF5. ARQ6. ACF3. SETUP4. Call Proceeding7.Alerting8.ConnectH.245 MessagesRTP Media Path关守运行模式（1）332022/7/18关守运行模式（2）342022/7/18关守运行模式（3）352022/

17、7/18H323网络的部署362022/7/18OUTLINEVOIP简介VOIP协议族媒体流传输信令H323 SIPMGCP声音处理NGNVOIP应用中的NAT问题372022/7/18WHAT IS SIPSession Initiation Protocol 构建在传输层上的信令协议定义了多个端点之间的会话建立修改终结382022/7/18SIP框架Session initiation.Multiple users.Interactive multimedia applications.392022/7/18ConferencingDistance LearningEmailVideo

18、ConferencingInstant MessagingVoice CallsMPEG, MP3, Audio, HTML,XMLPersonal MobilitySIP分布式结构402022/7/18Redirect ServerLocation ServerRegistrar ServerUser AgentProxy ServerGatewayPSTNSIP ComponentsProxy ServerUSER AGENT412022/7/18发起、接收和终结会话的应用. User Agent Clients (UAC) 发起会话的实体User Agent Server (UAS) 接

19、收会话的实体UAC和UAS都可以终结一个会话SIP 服务器422022/7/18SIP实体之间的交互432022/7/18SIP实体交互（重定向模式）442022/7/18SIP服务器链452022/7/18SIP协议栈结构462022/7/18SIP的特点命令和响应 UA Client UA Server基于文本的协议（HTTP Like)无状态（TRANSACTION）良好的伸缩性SIP地址 和数据业务的集成灵活性 扩展和对数据业务的支持错误名字命令和响应码的扩充承载的数据类型和DNS的集成天然的PRESENCE和移动支持可编程互操作性差不成熟472022/7/18SIP命令482022/

20、7/18SIP响应492022/7/18SIP响应（cont.)502022/7/18SIP消息512022/7/18SIP地址EXAMPLE:两部分组成协议类似于EMAIL的地址易于和WEB、电子邮件等数据业务的集成522022/7/18SIP编程532022/7/18SIP编程（cont.）542022/7/18PRESENCE是否在线用户的物理位置。例如，是在家里还是在公司 呼叫状态 可能的通信方式被叫的通话意愿 552022/7/18PRESENCE应用（1）自动会议 562022/7/18PRESENCE应用（2）订阅另外一个用户的通话状态572022/7/18SIP和移动58202

21、2/7/18SIP和移动592022/7/18SIP的发展IETF MMUSIC WG于定义的RFC2543 需要另外两个协议来实现完整的呼叫处理过程：RTP/RTCP和SDP各种草案的方向呼叫控制会议和群组通信NAT/FW穿透移动和服务器定位QoSAAA安全和H323以及PSTN信令的互操作Presence和Instance Message号码计划和呼叫路由交换配置和管理媒体传输 602022/7/18OUTLINEVOIP简介VOIP协议族媒体流传输信令H323SIP H323和SIP的比较MGCP声音处理NGNVOIP应用中的NAT问题612022/7/18H323和SIP二者完成和实现

22、的功能类似，是两个平行的协议622022/7/18H323和SIP呼叫控制动能632022/7/18H323和SIP高级特性642022/7/18H323和SIP伸缩性652022/7/18H323和SIP扩展性662022/7/18H323和SIP易于实现672022/7/18H323和SIP易于定制682022/7/18H323和SIP和数据业务的集成692022/7/18SIP地址SIP可以承载任意数据类型：SDPMIMEPRESENCE特性可以增强传统的业务H323和SIPSIP的互操作较差SIP的不同实体SIP的不同版本之间SIP的成熟度大量草案702022/7/18H323和SIP

23、总结712022/7/18H323和SIP的部署现状722022/7/18OUTLINEVOIP简介VOIP协议族媒体流传输信令H323SIPH323和SIP的比较 MGCP（Megaco/H248)声音处理NGNVOIP应用中的NAT问题732022/7/18What is MGCPMedia Gateway Control Protocol - A protocol for controlling telephony gateways from external call control elements called media gateway controllers or call a

24、gents. 742022/7/18MGCP的实体构成752022/7/18MGCP/H323/SIP的关系762022/7/18Call Agent or Media Gateway Controller(MGC)Call Agent or Media Gateway Controller(MGC)SIPMGCPMGCPMedia Gateway(MG)Media Gateway(MG)MGC管理多个MG772022/7/18Gateway A Gateway BAnalogPhone AAnalogPhone BCall AgentMedia Gateway ControllerMGCPM

25、GCPRTP/RTCPMGCP和SIP/H323互相补充的地方782022/7/18MGCP和SIP/H323相互竞争的地方792022/7/18MGCP命令Call Agent Commands:EndpointConfigurationNotificationRequestCreateConnectionModifyConnectionDeleteConnectionAuditEndpointAuditConnection802022/7/18Gateway Commands:NotifyDeleteConnectionRestartInProgressWhat is Megaco?A p

26、rotocol that is evolving from MGCP and developed jointly by ITU and IETF:Megaco - IETF.H.248 or H.GCP - ITU.参见IETF - Packetizer - 812022/7/18OUTLINEVOIP简介VOIP协议族媒体流传输信令H323SIPH323和SIP的比较MGCP（Megaco/H248)声音处理NGNVOIP应用中的NAT问题822022/7/18声音处理软件的工作线路、声学回声的抑制和消除活动声音检测舒适嘈音生成声音的编解码通常使用DSP来完成RTP的回放有时由DSP来完成832022/7/18MOS（平均影