数据通信与网络02基本概念ppt课件.ppt

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1、Chapter2BASICCONCEPTS第二章基本概念Generalconcept2.1Lineconfiguration（线路配置）2.2Topology（拓扑结构）2.3Transmissionmode（传输模式）2.4Categoriesofnetworks（网络类型）2.5Internetworks（网际互联）2.1LineConfigurationLineconfigurationreferstothewaytwoormorecommunicationdevicesattachtoalink.Alinkisthephysicalc

2、ommunicationpathwaythattransfersdatafromonedevicetoanother.LinkCategoriesofLineConfiguration2.1LineConfigurationLineconfigurationPoint-to-pointMultipoint2.1.1Point-to-Point(点到点连接)Apoint-to-pointlineconfigurationprovidesadedicatedlinkbetweentwodevices.Link1.Theentirecapacity

3、ofchannelisreservedfortransmissionbetweenthosetwodevice.2.Thelineconfigurationusewire,cable,microwaveorsatellitelinktoconnectthetwoends.2.1.1Point-to-Point两个设备间的专用的链路可以采用：导线、电缆、微波或卫星等。2.1.2Multipoint(多点连接)Amultipoint(alsocalledmultidrop)lineconfigurationisoneinwhichmorethan

4、twospecificdevicesshareasinglelink.Link2.1.2MultipointShareasinglelink：两个以上的设备共享一条链路。Themannerofsharedchannelcapacity:spatially(空分),temporally(时分).Spatiallysharedlineconfiguration:多个设备同时使用链路。Timesharedlineconfiguration:用户排队使用链路。2.2TopologyTopologyrefertothewayanetworkislaid

5、out,eitherphysicallyorlogically.※Twoormoredevicesconnecttoalink;twoormorelinksformatopology.2.2TOPOLOGYTherearefivebasictopologiespossible:mesh,star,tree,busandring.TopologyMeshStarBusRingTree2.2TOPOLOGYTherelationshipofdevicestobelinked:Peertopeer(对等式):设备平等的共享链路。ringandmes

6、htopologyprimary-secondary(主从式):主设备控制通信过程。starandtree※Bustopologyisequallyconvenientforeither2.2.1Mesh（网状拓扑）2.2.1MeshInameshtopology,everydevicehasadedicatedpoint-to-pointlinktoeveryotherdevice.Thetermdedicatedmeansthatthelinkcarriestrafficonlybetweenthetwodevicesitconnects

7、.Afullyconnectedmeshnetworkthereforehasn(n-1)/2physicalchannelstolinkndevices.Everydeviceonthenetworkmusthaven-1input/output(I/O)portsAdvantages:Theuseofdedicatedlinksguaranteesthateachconnectioncancarryitsdataload,thuseliminatingthetrafficproblemsthatcanoccurwhenlinksmustb

8、esharedbymultipledevicesrobust.Ifonelinkbecomesunusable,itdoesnotincapacitatetheen