清华大学课件_流媒体网络传输特性.ppt

Outline ReviewProvidingQoSintheInternet 五道口生活网五道口论坛 Review StreamingMediathreetypesofMMapp RTSP RTCP RTPApplicationadaptationsinbest effortnetworksdealingwithvariabledelay playoutbufferdealingwithpacketloss FECMDC dealingwithvariablebandwidth SVClikeFGS 五道口生活网五道口论坛 Real timeStreamingChallenges HighbandwidthAudioandvideomustbeplayedbackattheratetheyweresampled voicemaybeevenmoredifficult Multimediadatastreamsarebursty 五道口生活网五道口论坛 Real timeStreamingChallenges Multimediadatastreamsarebursty恒定比特率 CBR constantbit ratetraffic 以恒定比特率产生输出可变比特率 VBR variablebit ratetraffic 数据输率随时间变化 传输常以突变或跳变的形式出现 突变传输的特点是相对空闲的随机时段散布着突变数据 突变信息源在不同时段产生数目不定的数据 VBR视频流由两种因素引起 压缩算法和画面内容 五道口生活网五道口论坛 Internet Primaryreason PlatformformostnetworkingactivitiesIntegrateddataandmultimediaserviceoverasinglenetwork investments Notsuitableforreal timetrafficOffersonlybest effortquality 五道口生活网五道口论坛 Problemstobesolved ProvideenoughbandwidthProvidemulticasttoreducetrafficProvideprotocolsthathandlethecareoftimingissuesDelay Jitter QoS guaranteequalityReserveresourceontheinternetTransportprotocolsPresentationofthemultimediadata WAP Voice Chargingandpolicingmechaninsm 五道口生活网五道口论坛 QoS QoSisasetoftechnologiesthatenablesnetworkadministratorstomanagetheeffectsofcongestiononapplicationtrafficbyusingnetworkresourcesoptimallyor allocatedifferentresoursesfordifferentdataflows 五道口生活网五道口论坛 QoSDefinitions 五道口生活网五道口论坛 与媒体传输有关的QoS参数 五道口生活网五道口论坛 与媒体传输有关的QoS参数 五道口生活网五道口论坛 与媒体传输有关的QoS参数 五道口生活网五道口论坛 与媒体传输有关的QoS参数 五道口生活网五道口论坛 与媒体传输有关的QoS参数 应用 五道口生活网五道口论坛 与媒体传输有关的QoS参数 应用 五道口生活网五道口论坛 与媒体传输有关的QoS参数 管理 QoS管理的概念1 资源预定和计划 Reservation 2 QoS协商 negotiation 3 QoS映射 mapping 4 资源监控 Monitor 5 QoS承诺 promises 五道口生活网五道口论坛 QoSClasses Best effort NoguranteesatallSoftQoS differentiatedguarantessHardQoS fullguarantees 五道口生活网五道口论坛 HardRealTime GuaranteedServices ServicecontractNetworktoclient guaranteeadeterministicupperboundondelayforeachpacketinasessionClienttonetwork thesessiondoesnotsendmorethanitspecifiesAlgorithmsupportAdmissioncontrolbasedonworst caseanalysisPerflowclassification schedulingatrouters 五道口生活网五道口论坛 SoftRealTime ControlledLoad Predicative Service Servicecontract Networktoclient similarperformanceasanunloadedbest effortnetworkClienttonetwork thesessiondoesnotsendmorethanitspecifiesAlgorithmSupportAdmissioncontrolbasedonmeasurementofaggregatesSchedulingforaggregatepossible 五道口生活网五道口论坛 Outline ReviewProvidingQoSintheInternet 五道口生活网五道口论坛 ImprovingQOSinIPNetworks Thusfar makingthebestofbesteffort Future nextgenerationInternetwithQoSguaranteesRSVP signalingforresourcereservationsDifferentiatedServices differentialguaranteesIntegratedServices firmguaranteesExample guaranteesanaudioapplication1Mbps theremainingto0 5MbpstoWebtransfer 五道口生活网五道口论坛 ImprovingQOSinIPNetworks 五道口生活网五道口论坛 PrinciplesforQOSGuarantees Example 1MbpsIPphone FTPshare1 5Mbpslink burstsofFTPcancongestrouter causeaudiolosswanttogiveprioritytoaudiooverFTP packetmarkingneededforroutertodistinguishbetweendifferentclasses andnewrouterpolicytotreatpacketsaccordingly Principle1 五道口生活网五道口论坛 PrinciplesforQOSGuarantees more whatifapplicationsmisbehave audiosendshigherthandeclaredrate policing forcesourceadherencetobandwidthallocationsmarkingandpolicingatnetworkedge similartoATMUNI UserNetworkInterface provideprotection isolation foroneclassfromothers Principle2 五道口生活网五道口论坛 PrinciplesforQOSGuarantees more Allocatingfixed non sharable bandwidthtoflow inefficientuseofbandwidthifflowsdoesn tuseitsallocation Whileprovidingisolation itisdesirabletouseresourcesasefficientlyaspossible Principle3 五道口生活网五道口论坛 PrinciplesforQOSGuarantees more Basicfactoflife cannotsupporttrafficdemandsbeyondlinkcapacit