外文翻译论文题目:大型企业网络的设计与规划姓名:贾龙飞学号:201120210230班级:1122102班年级:2011级专业:网络工程学院:软件学院指导教师:王志波(讲师)完成时间:二〇一五年四月目录1.COMPUTERNETWORKS............................................3DATECOMMUNICATIONS..........................................32.ARCHITECTUREOFCOMPUTERNETWORKS............................41.TheOSIReferenceModel....................................42.TheTCP/IPReferenceModel.................................43.WIDEAREANETWORK............................................51.CIRCUITSWITCHEDNETWORKS..................................52.LEASEDLINENETWORKS......................................63.PACKETSWITCHINGNETWORKS..................................64.LOCALAREANETWORK...........................................71.Topology...................................................72.Transmissionmedia.........................................73.Mediumaccesscontrolmethods.............................71.计算机网络...................................................9数据通信.....................................................92.计算机网络的体系结构.........................................91.OSI参考模型..............................................102.TCP/IP参考模型...........................................103.广域网......................................................101.电路交换网................................................112.专线网....................................................113.分组交换网................................................114.局域网......................................................121.拓扑结构..................................................122.传输媒体..................................................123.媒体访问控制方法..........................................121.COMPUTERNETWORKSDATECOMMUNICATIONSTheendequipmentwhicheithergeneratesthedigitalinformationfortransmissionorusesthereceiveddigitaldatacanbecomputer,printers,keyboards,CRTs,andsoon.Thisequipmentgenerallymanipulatesdigitalinformationinternallyinwordunits—allthebitsthatmakeupawordinaparticularpieceofequipmentaretransferredinparallel.Digitaldata,whentransmitted,areinserialform.Paralleltransmissionofan8-bitwordrequireeightpairsoftransmissionlines—notatallcost-effective.Dataterminal(DTE)isageneralphraseencompassingallofthecircuitrynecessarytoperformparallel-to-serialandserial-to-parallelconversionsfortransmissionandreceptionrespectivelyandfordatalinkmanagement.TheUART(UniversalAsynchronousReceiver/Transmitter)andUSART(UniversalAsynchronous/AsynchronousReceiver/Transmitter)arethedevicesthatperformtheparallel-to-serialandserial-to-parallelconversions.TheprimaryDTEincludesalinecontrolunit(LCUorLinCo)whichcontrolstheflowofinformationinamultipointdatalinksystem.Astationcontroller(STACO)isthecorrespondingthatbelongedtothesubscriberinadatalinksystem.BetweentheDTEs,startingwiththemodems,wascommunicationsequipmentownedandmaintainedbyTelcoproperty.Datacommunicationsequipment(DCE)acceptstheserialdatastreamfromtheDTEandconvertsittosomeformofanalogsignalsuitablefortransmissiononvoice-gradelined.Atthereceiveend,theDCEperformsthereversefunctionofconvertingthereceivedanalogsignaltoaserialdigitaldatastream.ThesimplestformofDCEisamodem(modulator/demodulator)ordataset.Atthetransmitend,themodemcanbeconsideredaformofdigital-to-analogconverter,whileatthereceiveend,itcanconsideredaformofanalog-to-digitalconverter.Themostcommonofmodulationbymodemsarefrequencyshiftkeying(FSK),phaseshiftkeying(PSK),andquadratureamplitudemodulation(QAM).Thisisatypicallydatatransmissionmodeusingtheanalogtelephonelines.Ifyoutransmitdatabydigitalchannel(sometimesitiscalled“DigitalT-carrier”),apulseCodeModulation(PCM)equipmentmustbeused.Amicrowavetransmissionsystemcanalsobeusedforthedatacommunication.Finally,youcanusethesatellitecommunicationsystemfordatatransmission.IfthecablesandsignallevelsusedtointerconnecttheDTEandDCEwereleftunregulated,thevariationsgeneratedwouldprobablybeproportionaltothenumberofmanufacturers.ElectronicsindustriesAssociation(EIA),anorganizationofmanufactureswithestablishingtheDTEandmodem.Thisisa25-pincablewhosepinshavedesignatedfunctionsandspecifiedsignallevels.TheRS-232Cisanticipatedtobereplacedbyanupdatestandard.2.ARCHITECTUREOFCOMPUTERNETWORKSComputernetworkisacomplexconsistingoftwoormoreconnedcomputingunits,itisusedforthepurposeofdatacommunicationandresourceresourcesharing.Designofanetworkanditslogicalstructureshouldcomplywithasetofdesignprinciples,includingtheorganizationoffunctionsandthedescriptionofdataformatsandprocedure.Thisisthenetworkarchitectureandsocalledasasetoflayersandprotocols,becausethearchitectureisalayer-based.Inthenexttwosectionswewilldiscusstwoimportantnetworkarchitectures,theOSIreferencemodelandtheTCP/IPreferencemodel.1.TheOSIReferenceModelTheOSImodelisshowninFig.14-2(minusthephysicalmedium).ThismodelisbasedonaproposaldevelopedbytheInternationalStandardsOrganizations(OSI)asthefirststeptowardinternationalstandardizationoftheprotocolsusedinthevariouslayers.ThemodeliscalledtheISOOSI(OpenSystemInterconnection)ReferenceModelbecauseitdealswithconnectingopensystems--thatis,systemsthatareopenforcommunicationwithoth