2 IP Networking Overview Catatan :IP assumes delay and packet ordering problems
3 Delay budget deals with one-way delay, not a round-trip! Voice Delay with IPOne-Way, Mouth-to-Ear DelayDescription1-150 msSuitable for most delay sensitive applications like voice.msStill acceptable, but starts to influence voice quality. Communication can be annoying if no actions are taken.400 ms and greaterUnacceptable for most delay sensitive applications.Delay budget deals with one-way delay, not a round-trip!Catatan :
5 Major VoIP Protocols Catatan : VoIP Protocol Description H.323 ITU standard protocol for interactive conferencing.Evolved from H.320 ISDN standard.Flexible, complex.Media Gateway Control Protocol (MGCP)Emerging standard for Public Switched Telephone Network (PSTN) gateway control, thin device control.Session Initiation Protocol (SIP)IETF protocol for interactive and non-interactive conferencing.Simpler, but less mature, than H.323.Real-Time Transport Protocol (RTP)IETF standard media streaming protocol.Real-Time Transport Control Protocol (RTCP)Protocol that provides out-of-band control information for an RTP flow.Catatan :Low Latency Queuing (LLQ)Priority queuing technique that uses priority queuing-class-based weighted fair queuing (PQ-CBWFQ).
6 The PBX seizes a trunk line to the router, and forwards dial digits. Signaling from PBX to the RouterCatatan :The PBX seizes a trunk line to the router, and forwards dial digits.
7 Signaling Between Routers The Dial Plan Mapper reads the dial digits, and finds the address of the remote IP peer. The H.323 agent initiates a Q.931 call to the remote peer.Catatan :
8 Signaling from Router to PBX The remote H.323 agent seizes a PBX trunk, returns a Q.931 acknowledgment to the origin, and forwards dial digits to the PBXCatatan :
9 VoIP Bandwidth Consumption Coded Frame Size (bytes)Voice Frames in VoIP PacketIP+UDP+RTP Header Size (bytes)Layer 2 Header Size (bytes)Voice Bandwidth (Kbps)Layer 2 Technology UsedTotal Bandwidth RequiredCoding AlgorithmG.71164160240Ethernet II2690.4G.71164160240MLPPP782.8G.7116416022 (cRTP)MLPPP767.6Ethernet II (Cisco Default)G.7298202402634.4G.729820240MLPPP726.8Catatan :G.72982022 (cRTP)MLPPP711.6
10 VoIP QoS Building Blocks Devices AffectedIP Network IssueSolutionsBackbone speed and scaleBackbone routersHigh-performance routersPacket classificationEdge routersIP PrecedenceBandwidth management and admission controlEdge routersVoice compressionReal-Time Transport Protocol (RTP) header compressionGatekeepersCongestion managementEdge routersBackbone routersWeighted Random Early Detection (WRED)Catatan :Queue managementEdge routersBackbone routersLow Latency Queuing (LLQ)Other queuing techniques
11 RTP Header Compression RTP Headers are almost always 2 Bytes long when compressed.RTP header compression saves bandwidth by compressing packet headers across WAN links.Catatan :