计算机网络专业英语 课件 L1-7 Text 7 Physical and Logical Layout of Computer Networks

L1-7

Lesson1OverviewofComputerNetworks

Text7PhysicalandLogicalLayoutofComputerNetworks要点KeyPoints：从英语的角度理解专业词汇Level和layerThetransmissionmediausedtolinkdevicestoformacomputernetworkincludeelectricalcable(UTP/STPcables,telephonewires,coaxial

cables,andpowerlines),fiber

opticsandradiowaves.IntheOSImodel,thesearedefinedatlayers1and2–thephysicallayerandthedatalinklayer.Apartfromanyphysicaltransmissionmedium,networkscompriseadditionalbasicdevices,suchasnetworkinterfacecontrollers(NICs),repeaters,hubs,transceivers,bridges,switches,routers,modems,andfirewalls.Repeater：重复器，中继器Transceiver：收发器receiver电话机的听筒等Bridge：网桥

Switch：（铁道的）道岔switcherRouter:route路线fiberoptics/opticalfiberelectricalcable：与电有关的缆，电缆electriccable？Radiowave：无线电波从英语的角度理解专业词汇Thetransmissionmediausedtolinkdevicestoformacomputernetworkincludeelectricalcable(UTP/STPcables,telephonewires,coaxialcables,andpowerlines),fiberopticsandradiowaves.IntheOSImodel,thesearedefinedatlayers1and2–thephysicallayerandthedatalinklayer.Apartfromanyphysicaltransmissionmedium,networkscompriseadditionalbasicdevices,suchasnetworkinterfacecontrollers(NICs),repeaters,hubs,transceivers,bridges,switches,routers,modems,andfirewalls.Intreetopology,acentral“root”node(thetoplevelofthehierarchy)isconnectedtooneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thesecondlevel)withapoint-to-pointlinkbetweeneachofthesecondlevelnodesandthetoplevelcentral“root”node,whileeachofthesecondlevelnodesthatareconnectedtothetoplevelcentral“root”nodewillalsohaveoneormoreothernodesthatareonelevellowerinthehierarchy(i.e.,thethirdlevel)connectedtoit,alsowithapoint-to-pointlink,thetoplevelcentral“root”nodebeingtheonlynodethathasnoothernodeaboveitinthehierarchy–thehierarchyofthetreeissymmetrical,eachnodeinthenetworkhavingaspecificfixednumber“