C语言双语课件 CHAPTER2

计算机网络与通信

DataandComputerCommunications2.

协议体系结构,TCP/IP,互联网应用ProtocolArchitecture,TCP/IP,andInternet-BasedApplications

为什么需要协议体系结构简化的三层协议体系

TCP/IP协议体系结构

多媒体1ProtocolArchitecture,TCP/IP,andInternet-BasedApplicationsTodestroycommunicationcompletely,theremustbenorulesincommonbetweentransmitterandreceiver—neitherofalphabetnorofsyntax

—OnHumanCommunication,ColinCherry2Contents为什么需要协议体系结构简化的协议体系结构TCP/IP协议体系结构标准化的协议体系结构传统的互联网应用多媒体32.1TheNeedForProtocolArchitectureTotransferdataseveraltasksmustbeperformed:1.)thesourcemustactivatecommunicationspathorinformnetworkofdestination2.)thesourcemustmakesurethatdestinationispreparedtoreceivedata3.)thefiletransferapplicationonsourcemustconfirmfilemanagementprogramatdestinationispreparedtoacceptandstorefile4.)aformattranslationfunctionmayneedtobeperformediftheformatsonsystemsaredifferent4FunctionsofProtocolArchitecturebreakslogicintosubtaskmoduleswhichareimplementedseparatelymodulesarearrangedinaverticalstackeachlayerinthestackperformsasubsetoffunctionsreliesonnextlowerlayerforprimitivefunctionschangesinonelayershouldnotrequirechangesinotherlayers5KeyFeaturesofaProtocolAprotocolisasetofrulesorconventionsthatallowpeerlayerstocommunicate.Thekeyfeaturesofaprotocolare:SyntaxformatofdatablocksSemanticscontrolinformationforcoordinationanderrorhandlingTimingspeedmatchingandsequencing语法语义时序关系6Contents为什么需要协议体系结构简化的协议体系结构TCP/IP协议体系结构标准化的协议体系结构传统的互联网应用多媒体72.2ASimpleProtocolagentsinvolved:applicationscomputersnetworksexamplesofapplicationsincludefiletransferandelectronicmailtheseexecuteoncomputersthatsupportmultiplesimultaneousapplications8CommunicationLayerscommunicationtasksareorganizedintothreerelativelyindependentlayers: ApplicationlayerContainslogictosupportapplicationsTransportlayerprovidesreliabledatatransferNetworkaccesslayerconcernedwiththeexchangeofdata（应用层）（传输层）(网络接入层)9NetworkAccessLayer网络接入层coverstheexchangeofdatabetweenanendsystemandthenetworkthatitisattachedtoconcernedwithissueslike:destinationaddressprovisioninvokingspecificserviceslikepriorityaccessto&routingdataacrossanetworkfortwoendsystemsattachedtothesamenetwork10TransportLayer传输层11ApplicationLayer应用层containsthelogicneededtosupportuserapplicationsseparatemoduleisneededforeachtypeofapplication12ProtocolArchitectureandNetworks13ProtocolsinaSimplifiedArchitecture14Addressing寻址Twolevelsofaddressingareneeded:eachcomputeronthenetworkhasauniquenetworkaddresseachapplicationhasanaddressthatisuniquewiththatcomputer(SAPs)15ProtocolDataUnit(PDU)

协议数据单元thecombinationofdataandcontrolinformationisaprotocoldataunit(PDU)typicallycontrolinformationiscontainedinaPDUheadercontrolinformationisusedbythepeertransportprotocolatcomputerBheadersmayinclude:sourceport,destinationport,sequencenumber,anderror-detectioncode16NetworkAccessProtocolafterreceivingsegmentfromtransportlayer,thenetworkaccessprotocolmustrequesttransmissionoverthenetworkthenetworkaccessprotocolcreatesanetworkaccessPDU(packet)withcontrolinformationheaderincludes:sourcecomputeraddressdestinationcomputeraddressfacilitiesrequests17Contents为什么需要协议体系结构简化的协议体系结构TCP/IP协议体系结构标准化的协议体系结构传统的互联网应用多媒体18TCP/IPProtocolArchitectureResultofprotocolresearchanddevelopmentconductedonARPANETReferredtoasTCP/IPprotocolsuiteTCP/IPcomprisesalargecollectionofprotocolsthatareInternetstandards19TCP/IPLayersandExampleProtocols20PhysicalLayercoversthephysicalinterfacebetweencomputerandnetworkconcernedwithissueslike:characteristicsoftransmissionmediumnatureofthesignalsdatarates21NetworkAccessLayercoverstheexchangeofdatabetweenanendsystemandthenetworkthatitisattachedtoconcernedwithissueslike:destinationaddressprovisioninvokingspecificserviceslikepriorityaccessto&routingdataacrossanetworkfortwoendsystemsattachedtothesamenetwork22InternetLayerimplementsproceduresneededtoallowdatatotravelacrossmultipleinterconnectednetworksusestheInternetProtocol(IP)toprovideroutingfunctionimplementedinendsystemsandrouters23Host-to-Host(Transport)LayerconcernedwithprovidingreliabledeliveryofdatacommonlayersharedbyallapplicationsmostcommonlyusedprotocolistheTransmissionControlProtocol(TCP)24OperationofTCP/IP25TCP/IPAddressRequirementsTwolevelsofaddressingareneeded:eachhostonasubnetworkmusthaveauniqueglobalinternetaddresseachprocesswithahostmusthaveanaddress(knownasaport)thatisuniquewithinthehostIPaddressPortnumber26OperationofTCP/IP27TransmissionControlProtocol(TCP)TCPisthetransportlayerprotocolformostapplicationsTCPprovidesareliableconnectionfortransferofdatabetweenapplicationsATCPsegmentisthebasicprotocolunitTCPtrackssegmentsbetweenentitiesfordurationofeachconnection28TCPHeader29UserDatagramProtocol

(UDP)alternativetoTCPdoesnotguaranteedelivery,preservationofsequence,orprotectionagainstduplicationaddsportaddressingcapabilitytoIPusedwithSimpleNetworkManagementProtocol(SNMP)30UDPHeader31IPHeader32IPv6ProvidesenhancementsoverexistingIPDesignedtoaccommodatehigherspeedsandthemixofgraphicandvideodataDrivingforcewastheneedformoreaddressesduetogrowthoftheInternetIPv6includes128-bitsourceanddestinationaddressfields33IPv6Header34SomeTCP/IPProtocols35思考题协议是什么？为什么需要协议？协议构成的基本要素是什么？协议体系结构为什么采用分层的方法？优缺点？三层简单协议体系结构中，各层协议完成的功能？网络系统中的两级地址是？靠什么来传递对等层协议相关信息？协议体系结构的工作？TCP/IP协议包括哪五个部分？36Contents为什么需要协议体系结构简化的协议体系结构TCP/IP协议体系结构标准化的协议体系结构传统的互联网应用多媒体37协议分层的理解请举一日常生活中的例子来形象地描述该模型中各层的peer-to-peerprotocol（对等协议）和上下层之间的interface（接口）。北大学生张明给理工大学生李强写信的例子

张明写信李强读信

封入信封拆开信封投入信箱从信箱中取信件收信分检装邮包开邮包选路投递邮包送转运站从转运站取回邮包装列车箱发运列车箱卸包送转运站中文姓名地址目的地址目的站38张明给李强写信的通信协议体系结构图例张明（发送方）李强（接收方）2/1接口3/2接口4/3接口第4层第3层第2层第1层第2层对等协议第1层对等协议第3层对等协议第4层对等协议写信读信封信投信收信分检装包转运邮包装车卸车取回邮包投递选路拆包拆信取信发车到站铁轨（传输媒体）392.4StandardizedProtocolArchitectures40LayerSpecificStandards

特定层的标准41OSIStandardizationframeworkforstandardizationwasmotivatorlowerlayersareconcernedwithgreaterlevelsofdetailseachlayerprovidesservicestothenexthigherlayerthreekeyelements:ProtocolspecificationServicedefinitionAddressing42PrimitiveTypesREQUEST请求AprimitiveissuedbyaserviceusertoinvokesomeserviceandtopasstheparametersneededtospecifyfullytherequestedserviceINDICATION指示Aprimitiveissuedbyaserviceprovidereitherto:indicatethataprocedurehasbeeninvokedbythepeerserviceuserontheconnectionandtoprovidetheassociatedparameters,ornotifytheserviceuserofaprovider-initiatedactionRESPONSE

响应AprimitiveissuedbyaserviceusertoacknowledgeorcompletesomeprocedurepreviouslyinvokedbyanindicationtothatuserCONFIRM

证实Aprimitiveissuedbyaserviceprovidertoacknowledgeorcompletesomeprocedurepreviouslyinvokedbyarequestbytheserviceuser43ServicePrimitives（原语）andParametersdefineservicesbetweenadjacentlayersusing:primitivestospecifyfunctionperformedparameterstopassdataandcontrolinfo44Contents为什么需要协议体系结构简化的协议体系结构TCP/IP协议体系结构标准化的协议体系结构传统的互联网应用多媒体45InternetApplicationsApplicationsthatoperateontopofTCPinclude:SMTPFTPSSHTCP46Contents为什么需要协议体系结构简化的协议体系结构TCP/IP协议体系结构标准化的协议体系结构传统的互联网应用多媒体47MultimediaTerminology48MultimediaTerminologyaudiogenerallyencompassessoundsthatareproducedbyahuman,telephonyandrelatedvoicecommunicationstechnologyimagesupportsthecommunicationofindividualpictures,charts,ordrawingsvideoservicecarriessequencesofpicturesintimetextisinformationthatcanbeenteredviaakeyboardandisdirectlyreadableandprintable49MultimediaApplicationsMultimediainformationsystems

databases,informationkiosks,hypertexts,electronicbooks,andmultimediaexpertsystemsMultimediacommunicationsystems

computer-supportedcollaborativework,videoconferencing,streamingmedia,andmultimediateleservicesMultimediaentertainmentsystems

3Dcomputergames,multiplayernetworkgames,infotainment,andinteractiveaudiovisualproductionsMultimediabusinesssystems

immersiveelectroniccommerce,marketing,multimediapresentations,videobrochures,virtualshoppingMultimediaeducationalsystems

electronicbooks,flexibleteachingmaterials,simulationsystems,automatictesting,distancelearning50DomainsofMultimediaSystemsandExampleApplications51ElasticandInelasticTrafficcanadjusttodelayandthroughputchangesacrossaninternet-traditional“data”styleTCP/IPtrafficdoesnoteasilyadapttochangesindelayandthroughput-“real-time”trafficsuchasvoiceandvideoElasticTraffic弹性流量InelasticTraffic非弹性流量52MultimediaTechnologies53SummaryintroducedneedforprotocolarchitectureTCP/IPprotocolarchitectureprotocolarchitecturestandardizationmultimediaapplicationneeds协议的关键要素TCP/IP协议体系结构54AssignmentsPart12.1Multiplechoice1.WhichofthefollowingisNOTthekeyelementsofaprotocol?A.syntax

B.semantics

C.rule

D.timing

552.1Multiplechoice2-5.ThelayersinTCP／IPprotocolarchitectureare2

,Intransportlayer,TCPprovides3

datatransmission，andUDPprovides4datatransmission.Innetworklayer,IPprovides

5packettransmission.

2.A．transportlayer,internetlayer,networkaccesslayer,physicallayerB．applicationlayer,transportlayer,internetlayer,networkaccesslayer,physicallayerC．transportlayer,internetlayer,ATMlayer,physicallayerD．transportlayer,networklayer,datalinklayer,physicallayer3.A．connectionoriented,notreliableB．connectionless,notreliableC．connectionoriented,reliableD．connectionless,reliable4.A．connectionlessB．connectionorientedC．connectionless,reliableD．connectionoriented,notreliable5.A．connectionoriented,reliableB．connectionless,reliableC．connectionoriented,notreliableD．connectionless,notreliable562.1Multiplechoice6.Networkarchitecturecanbedefinedas：A.animplementationofcomputernetworksB.asoftwaremoduletoimplementtechniquesanddataprocessingC.asetofrulesandstandardstosetuporusehardware(software)forcommunication.D.astandarddefinedbyISO.7.Communicationsystemhasdifferentkindsofconnections.Internetconnectionis

ina:A.pointtopointlinkB.MultinodebroadcastnetworkC.switchingnetworkD.Packetswitchingnetwork

572.1Multiplechoice8.ThelayersofTCP/IPprotocolarchitectureare(fromtoptobottom):A.application,session,transport,networkaccess,physicalB.application,transport,network,datalink,physicalC.application,transport,internet,networkaccess,physicalD.application,presentation,transport,internet,networkaccess

582.1Multiplechoice9.Regardlessofthenatureoftheapplicationsthatareexchangingdata,thereisusuallyarequirementthatdatabeexchangedreliably，thisisreferredtoasthe（）.A.transportlayerB.applicationlayerC.physicallayerD.networkaccesslayer592.1Multiplechoice10.Thecombinationofdatafromthenexthigherlayerandcontrolinformationisknownasa().

A.datalink B.headerC.protocoldataunit D.sequencenumber

11.The()layerisconcernedwiththeexchangeofdatabetweenanendsystem(server,workstation,etc.)andthenetworktowhichitisattached.

A.transport B.applicationC.networkaccess D.physical602.1Multiplechoice12.Themainfunctionofthephysicallayeristotransfer（）correctly.A.bitstreamB.framesC.packetsD.datagram13.The()isusedatthislayertoprovidetheroutingfunctionacrossmultiplenetworks.A.TransmissionControlProtocol

B.InternetProtocolC.UserDatagramProtocolD.FileTransferProtocol612.2TermsDefinitionProtocolPDUFileTransferProtocolInternetProtocolUserDatagramProtocol622.3FillintheBlanksInlayeredmodel,whenapplicationdatatransmitfromupperlayertolowerlayer,eachlayerappendsa____,containingprotocolcontrolinformation.Thepeerlayerscommunicatebymeansofformattedblocksofdatathatobeyasetofrulesorconventionsknownasa____.

632.4AnswerQuestions

1.Whatarethekeyfeaturesofaprotocol?2.GivethefunctionsofeachlayerofTCP/IP.64AssignmentsPart22.5MultipleChoice1.Thepurposeofflowcontrolis:A.errorcontrolling B.timingC.orderdelivery D.topreventreceiveroverload2.Eachprocesswithahostmusthaveanaddressthatisuniquewithinthehost;thisallowsthehost-to-hostprotocol(TCP)todeliverdatatotheproperprocess.Theseaddressesareknownas()：A.globalinternetaddressB.portsC.networkaddressD.computeraddress652.5MultipleChoice3.The()isconcernedwithspecifyingthecharacteristicsofthetransmissionmedium,thenatureofthesignals,thedatarate,andrelatedmatters.A.NetworkaccesslayerB.physicallayerC.transportlayerD.Internetlayer4.IPappendsaheaderofcontrolinformationtoeachsegmenttoforman().A.IPsegmentB.IPpacketC.IPstream

D.IPdatagram662.5MultipleChoice5.Communicationbetweenpeerlayeratdifferentnodesneeds：A.interfaceB.peerprotocolC.electricalsignalD.transmissionmedia6.()characteristicofthephysicallayerrelatestothephysicalpropertiesoftheinterfacetoatrans