CCNA 1-4 TCP中的传输层.ppt

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1、BuildingaSimpleNetworkUnderstandingtheTCP/IPTransportLayerTransportLayerSessionmultiplexingSegmentationFlowcontrol(whenrequired)Connection-oriented(whenrequired)Reliability(whenrequired)Reliablevs.Best-EffortComparisonOperatesattransportlayerofOSIandTCP/IPmodels

2、ProvidesapplicationswithaccesstothenetworklayerwithouttheoverheadofreliabilitymechanismsIsaconnectionlessprotocolProvideslimitederrorcheckingProvidesbest-effortdeliveryHasnodata-recoveryfeaturesUDPCharacteristicsUDPHeaderTCPCharacteristicsTransportlayeroftheTCP/I

3、PstackAccesstothenetworklayerforapplicationsConnection-orientedprotocolFull-duplexmodeoperationErrorcheckingSequencingofdatapacketsAcknowledgementofreceiptData-recoveryfeaturesTCPHeaderFiletransferFTPTFTPNetworkFileSystemE-mailSimpleMailTransferProtocolRemotelogi

4、nTelnetrloginNetworkmanagementSimpleNetworkManagementProtocolNamemanagementDomainNameSystemTCP/IPApplicationLayerOverviewMappingLayer3toLayer4MappingLayer4toApplicationsEstablishingaConnectionThree-WayHandshakeCTL=WhichcontrolbitsintheTCPheaderaresetto1FlowContr

5、olTCPAcknowledgmentFixedWindowingTCPSlidingWindowingTCPSequenceandAcknowledgmentNumbersSummaryThepurposeofthetransportlayeristohidethenetworkrequirementsfromtheapplicationlayer.Connection-orientedtransportprovidesreliabletransport;connectionlesstransportprovidesb

6、est-efforttransport.UDPisaprotocolthatoperatesatthetransportlayerandprovidesapplicationswithaccesstothenetworklayerwithouttheoverheadofthereliabilitymechanismsofTCP.UDPisaconnectionless,best-effortdeliveryprotocol.TCPisaprotocolthatoperatesatthetransportlayerandp

7、rovidesapplicationswithaccesstothenetworklayer.TCPisconnection-oriented,provideserrorchecking,deliversdatareliably,operatesinfull-duplexmode,andprovidessomedatarecoveryfunctions.Summary(Cont.)TCP/IPsupportsanumberofapplications,includingFTP(supportsbidirectionalb

8、inaryandASCIIfiletransfers),TFTP(transfersconfigurationfilesandCiscoIOSimages),andTelnet(providescapabilitytoremotelyaccessanothercomputer).IPusesaprotocolnumb