IP网络技术基础课件(英文).ppt

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1、End-to-EndProtocolOutlineSimpleDemultiplexer(UDP)ReliableByte-Stream(TCP)ConnectionEstablishment/TerminationSlidingWindowRevisitedFlowControl1TheLayeredNetworkStackPhysicalLayerApplicationLayerTransportLayer(TCP/UDP)NetworkLayer(IP)DataLinkLayerInternetStackPhysicalLayerSessionLayerTransportLayer

2、NetworkLayerDataLinkLayerOSIStackPresentationLayerApplicationLayer2End-to-EndProtocolsUnderlyingbest-effortnetworkdropmessagesre-ordersmessagesdeliversduplicatecopiesofagivenmessagelimitsmessagestosomefinitesizedeliversmessagesafteranarbitrarilylongdelayCommonend-to-endservicesguaranteemessagedel

3、iverydelivermessagesinthesameordertheyaresentdeliveratmostonecopyofeachmessagesupportarbitrarilylargemessagessupportsynchronizationallowthereceivertoflowcontrolthesendersupportmultipleapplicationprocessesoneachhost3Transportlayerusesthenetworklayer,tosendandreceivedata.TransportProtocolDataUnit(T

4、PDU)EachlayeraddsitspartTCPsegment,IPpacket,DatalinkframeOverviewofTransportLayer4OverviewofTransportLayer(cont.)5Twotypesoftransportservicesconnection-orientedconnectionlessEnd-to-EndProtocols6SimpleDemultiplexor(UDP)TransportprotocolaboveIPsimplypassesIPthroughtotheupper(application)layersUnre

5、liableandunordereddatagramserviceAddsmultiplexingNoflowcontrolEndpointsidentifiedbyportsservershavewell-knownportsFTP-21,Telnet-23,http-80,pop-110,DNS-537UDP“Features”Givesapp’stheoptiontosendpacketsunreliablyUsefulformulticastapp’sLowdelaytransmissionforinteractivetext/audio/videoMinimalconnecti

6、onstate:“connectionless”MinimalconnectionsetuptimeNocongestioncontrol–blastawayBuildownapplication-levelprotocolontopofUDP8UDPUDPHeader:Only8bytes!(vs.IP20bytesheader)SourceportforUDPsendingprocessDestportforUDPreceivingprocessLengthinbytesofUDPheader+payloadChecksumoverUDPheader+payloadSourcePor

7、t#Dest.Port#UDPlengthChecksum1632UDPpayloaddataUDPpayloadIPhdrUDPhdrErrorDetection9ErrorDetectionWhyisthereerrordetectioninthetransportlayergiventhatthesamefunctionisprovidedbythedatalinklayerReliabletransmissionalonge