《软考网络工程师资料_OSI体系模型》由会员分享，可在线阅读，更多相关《软考网络工程师资料_OSI体系模型（41页珍藏版）》请在金锄头文库上搜索。
1、国家软件资格水平考试 网络工程师 王维轩 Objectives Oncompletionofthischapter youwillbeabletoperformthefollowingtasks DescribehowdatatrafficisexchangedbetweensourceanddestinationdevicesIdentifytherolesandfunctionsofahub switch androuter andwheretheybestfitinthenetworkIdentifytheIPprotocolstack itsprotocollayerfunctions
2、 andcommonlyusedIPprotocolsIdentifyIPaddressclasses IPaddresses IPsubnetmasks IPnetworknumbers subnetnumbers andpossiblehostnumbers 网络体系结构 DefiningComponentsoftheNetwork MainOffice BranchOffice HomeOffice MobileUsers Internet Floor2 Floor1 ServerFarm DefiningtheComponentsofaNetwork BranchOffice Tele
3、commuter ISDN Remote Campus NetworkStructureDefinedbyHierarchy DistributionLayer CoreLayer AccessLayer AccessLayerCharacteristics Endstationentrypointtothenetwork AccessLayer DistributionLayercharacteristics AccessLayerAggregationPointRoutestrafficBroadcast MulticastDomainsMediaTranslationSecurityPo
4、ssiblepointforremoteaccess DistributionLayer CoreLayerCharacteristics FasttransporttoenterpriseservicesNopacketmanipulation CoreLayer OSIModelOverview Application Upper Layers Session Presentation Application OSIModelOverview DataFlowLayers TransportLayer DataLink NetworkLayer Physical RoleofApplica
5、tionLayers TelnetFTP UserInterface EXAMPLES Application TelnetFTP ASCIIEBCDICJPEG UserInterface HowdataispresentedSpecialprocessingsuchasencryption EXAMPLES Presentation Application RoleofApplicationLayers TelnetFTP ASCIIEBCDICJPEG Keepingdifferentapplications dataseparate UserInterface Howdataispre
6、sentedSpecialprocessingsuchasencryption OperatingSystem ApplicationAccessScheduling EXAMPLES Session Presentation Application RoleofApplicationLayers Keepingdifferentapplications dataseparate UserInterface HowdataispresentedSpecialprocessingsuchasencryption TransportLayer DataLink NetworkLayer Physi
7、cal EXAMPLES Session Presentation Application RoleofApplicationLayers RoleofDataFlowLayers EIA TIA 232V 35 EXAMPLES Physical MovebitsbetweendevicesSpecifiesvoltage wirespeedandpin outcables 802 3 802 2HDLC EIA TIA 232V 35 EXAMPLES RoleofDataFlowLayers DataLink Physical Combinesbitsintobytesandbytesi
8、ntoframesAccesstomediausingMACaddressErrordetectionnotcorrection MovebitsbetweendevicesSpecifiesvoltage wirespeedandpin outcables 802 3 802 2HDLC EIA TIA 232V 35 IPIPX EXAMPLES RoleofDataFlowLayers Network DataLink Physical CombinesbitsintobytesandbytesintoframesAccesstomediausingMACaddressErrordete
9、ctionnotcorrection MovebitsbetweendevicesSpecifiesvoltage wirespeedandpin outcables Providelogicaladdressingwhichroutersuseforpathdetermination TCPUDPSPX 802 3 802 2HDLC EIA TIA 232V 35 IPIPX EXAMPLES RoleofDataFlowLayers Transport DataLink Physical ReliableorunreliabledeliveryErrorcorrectionbeforer
10、etransmit CombinesbitsintobytesandbytesintoframesAccesstomediausingMACaddressErrordetectionnotcorrection MovebitsbetweendevicesSpecifiesvoltage wirespeedandpin outcables Network Providelogicaladdressingwhichroutersuseforpathdetermination TCPUDPSPX 802 3 802 2HDLC EIA TIA 232V 35 IPIPX Presentation A
11、pplication Session EXAMPLES RoleofDataFlowLayers ReliableorunreliabledeliveryErrorcorrectionbeforeretransmit CombinesbitsintobytesandbytesintoframesAccesstomediausingMACaddressErrordetectionnotcorrection MovebitsbetweendevicesSpecifiesvoltage wirespeedandpin outcables Transport DataLink Physical Net
12、work Providelogicaladdressingwhichroutersuseforpathdetermination EncapsulatingData Transport DataLink Physical Network UpperLayerData UpperLayerData TCPHeader Data IPHeader Data LLCHeader 0101110101001000010 Data MACHeader Presentation Application Session Segment Packet Bits Frame PDU UpperLayerData
13、 De encapsulatingData LLCHdr IP TCP UpperLayerData MACHeader IP TCP UpperLayerData LLCHeader TCP UpperLayerData IPHeader UpperLayerData TCPHeader 0101110101001000010 Transport DataLink Physical Network Presentation Application Session Application Presentation Session Transport Network DataLink Physi
14、cal OSIModel PDU FunctionalResponsibilities Examples WrittenExercise OSIModel PhysicalLayerFunctions DefinesMediatypeConnectortypeSignalingtype Ethernet 802 3 V 35 Physical EIA TIA 232 PhysicalLayer Ethernet 802 3 Hub Hosts Host 10Base2 ThinEthernet10Base5 ThickEthernet 10BaseT TwistedPair HubsOpera
15、teatPhysicallayer A B C D Physical AlldevicesinthesamecollisiondomainAlldevicesinthesamebroadcastdomainDevicessharethesamebandwidth Hubs OneCollisionDomain MoreendstationsmeansmorecollisionsCSMA CDisused DataLinklayerFunctions DefinesPhysicalsourceanddestinationaddressesHigherlayerprotocol ServiceAc
16、cessPoint associatedwithframeNetworktopologyFramesequencingFlowcontrolConnection orientedorconnectionless DataLink Physical EIA TIA 232v 35 Ethernet FrameRelay HDLC 802 2 802 3 Data Sourceadd FCS Length Destadd Variable 2 6 6 4 0000 0Cxx xxxx Vendorassigned IEEEassigned MACLayer 802 3 DataLinkLayerFunctions cont Preamble EthernetIIuses Type hereanddoesnotuse802 2 MACAddress 8 Bytes EachsegmenthasitsowncollisiondomainAllsegmentsareinthesamebroadcastdomain DataLink SwitchesandBridgesOperateatDataL
