CCNA培训讲义(1)

1-1第一天CCNA1-2协议基础1-3OSIModelOverviewDataFlowLayersTransportData-LinkNetworkPhysicalApplication(Upper)LayersSessionPresentationApplication1-4RoleofApplicationLayersTelnetFTPUserInterfaceExamplesApplication1-5TelnetFTPASCIIEBCDICJPEGUserInterface•Howdataispresented•SpecialprocessingsuchasencryptionExamplesPresentationApplicationRoleofApplicationLayers1-6TelnetFTPASCIIEBCDICJPEGKeepingdifferentapplications’dataseparateUserInterface•Howdataispresented•SpecialprocessingsuchasencryptionOperatingSystem/ApplicationAccessSchedulingExamplesSessionPresentationApplicationRoleofApplicationLayers1-7•Keepingdifferentapplications’dataseparate•Userinterface•Howdataispresented•SpecialprocessingsuchasencryptionTelnetFTPASCIIEBCDICJPEGOperatingSystem/ApplicationAccessSchedulingTransportData-LinkNetworkPhysicalExamplesSessionPresentationApplicationRoleofApplicationLayers1-8RoleofDataFlowLayersEIA/TIA-232V.35ExamplesPhysical•Movebitsbetweendevices•Specifiesvoltage,wirespeed,andpin-outcables1-9802.3/802.2HDLCEIA/TIA-232V.35ExamplesRoleofDataFlowLayersDataLinkPhysical•Combinesbitsintobytesandbytesintoframes•AccesstomediausingMACaddress•Errordetectionnotcorrection•Movebitsbetweendevices•Specifiesvoltage,wirespeed,andpin-outcables1-10802.3/802.2HDLCEIA/TIA-232V.35IPIPXExamplesRoleofDataFlowLayersNetworkDataLinkPhysical•Combinesbitsintobytesandbytesintoframes•AccesstomediausingMACaddress•Errordetectionnotcorrection•Movebitsbetweendevices•Specifiesvoltage,wirespeed,andpin-outcablesProvidelogicaladdressingthatroutersuseforpathdetermination1-11TCPUDPSPX802.3/802.2HDLCEIA/TIA-232V.35IPIPXExamplesRoleofDataFlowLayersTransportDataLinkPhysical•Reliableorunreliabledelivery•Errorcorrectionbeforeretransmit•Combinesbitsintobytesandbytesintoframes•AccesstomediausingMACaddress•Errordetectionnotcorrection•Movebitsbetweendevices•Specifiesvoltage,wirespeed,andpin-outcablesNetworkProvidelogicaladdressingthatroutersuseforpathdetermination1-12TCPUDPSPX802.3/802.2HDLCEIA/TIA-232V.35IPIPXPresentationApplicationSessionExamplesRoleofDataFlowLayers•Reliableorunreliabledelivery•Errorcorrectionbeforeretransmit•Combinesbitsintobytesandbytesintoframes•AccesstomediausingMACaddress•Errordetection,notcorrection•Movebitsbetweendevices•Specifiesvoltage,wirespeed,andpinoutcablesTransportData-LinkPhysicalNetwork•Providelogicaladdressingthatroutersuseforpathdetermination1-13EncapsulatingDataTransportData-LinkPhysicalNetworkUpper-LayerDataUpper-LayerDataTCPHeaderDataIPHeaderDataLLCHeader0101110101001000010DataMACHeaderPresentationApplicationSessionSegmentPacketBitsFramePDUFCSFCS1-14Upper-LayerDataDe-encapsulatingDataLLCHdr+IP+TCP+Upper-LayerDataIP+TCP+Upper-LayerDataTCP+Upper-LayerDataUpper-LayerData0101110101001000010TransportData-LinkPhysicalNetworkPresentationApplicationSession1-15TCP/IPProtocolStack7654325432ApplicationPresentationSessionTransportNetworkData-LinkPhysical1ApplicationTransportInternetData-LinkPhysical11-16ApplicationLayerOverview*UsedbytheRouterApplicationTransportInternetData-LinkPhysicalFileTransfer-TFTP*-FTP*-NFSE-Mail-SMTPRemoteLogin-Telnet*-rlogin*NetworkManagement-SNMP*NameManagement-DNS*1-17TransportLayerOverviewTransmissionControlProtocol(TCP)UserDatagramProtocol(UDP)ApplicationTransportInternetData-LinkPhysicalConnection-OrientedConnectionless1-18TCPSegmentFormatSourcePort(16)DestinationPort(16)SequenceNumber(32)HeaderLength(4)AcknowledgmentNumber(32)Reserved(6)CodeBits(6)Window(16)Checksum(16)Urgent(16)Options(0or32ifAny)Data(Varies)20BytesBit0Bit15Bit16Bit311-19PortNumbersTCPPortNumbersFTPTransportLayerTELNETDNSSNMPTFTPSMTPUDPApplicationLayer2123255369161RIP5201-20TCPPortNumbersSourcePortDestinationPort…HostA102823…SPDPHostZTelnetZDestinationport=23.SendpackettomyTelnetapplication.1-21SendSYN(seq=100ctl=SYN)SYNReceivedHostAHostBTCPThree-WayHandshake/OpenConnection11-22SendSYN(seq=100ctl=SYN)SYNReceivedSendSYN,ACK(seq=300ack=101ctl=syn,ack)HostAHostBSYNReceived12TCPThree-WayHandshake/OpenConnection1-23SendSYN(seq=100ctl=SYN)SYNReceivedSendSYN,ACK(seq=300ack=101ctl=syn,ack)Established(seq=101ack=301ctl=ack)HostAHostB123SYNReceivedTCPThree-WayHandshake/OpenConnection1-24TCPSimpleAcknowledgmentWindowSize=1SenderReceiver1-25TCPSimpleAcknowledgmentWindowSize=1SenderReceiverSend1Receive11-26TCPSimpleAcknowledgmentWindowSize=1SenderReceiverSend1Receive1ReceiveACK2SendACK21-27TCPSimpleAcknowledgmentWindowSize=1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive21-28TCPSimpleAcknowledgmentWindowSize=1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK31-29TCPSimpleAcknowledgmentWindowSize=1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive31-30WindowSize=1SenderReceiverSend1Receive1ReceiveACK2SendACK2Send2Receive2ReceiveACK3SendACK3Send3Receive3ReceiveACK4SendACK4TCPSimpleAcknowledgment1-31TCPSequenceandAcknowledgmentNumbersSourcePortDestinationPort…SequenceAcknowledgmentSourceDest.Seq.Ack.102823101Ijustsentnumber10.1-32TCPSequenceandAcknowledgmentNumbersIjustgotnumber10,nowInee