C語言雙語課件 CHAPTER2

計算機網絡與通信

DataandComputerCommunications2.

協議體系結構,TCP/IP,互聯網應用ProtocolArchitecture,TCP/IP,andInternet-BasedApplications

為什么需要協議體系結構簡化的三層協議體系

TCP/IP協議體系結構

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

—OnHumanCommunication,ColinCherry2Contents為什么需要協議體系結構簡化的協議體系結構TCP/IP協議體系結構標準化的協議體系結構傳統的互聯網應用多媒體32.1TheNeedForProtocolArchitectureTotransferdataseveraltasksmustbeperformed:1.)thesourcemustactivatecommunicationspathorinformnetworkofdestination2.)thesourcemustmakesurethatdestinationispreparedtoreceivedata3.)thefiletransferapplicationonsourcemustconfirmfilemanagementprogramatdestinationispreparedtoacceptandstorefile4.)aformattranslationfunctionmayneedtobeperformediftheformatsonsystemsaredifferent4FunctionsofProtocolArchitecturebreakslogicintosubtaskmoduleswhichareimplementedseparatelymodulesarearrangedinaverticalstackeachlayerinthestackperformsasubsetoffunctionsreliesonnextlowerlayerforprimitivefunctionschangesinonelayershouldnotrequirechangesinotherlayers5KeyFeaturesofaProtocolAprotocolisasetofrulesorconventionsthatallowpeerlayerstocommunicate.Thekeyfeaturesofaprotocolare:SyntaxformatofdatablocksSemanticscontrolinformationforcoordinationanderrorhandlingTimingspeedmatchingandsequencing語法語義時序關系6Contents為什么需要協議體系結構簡化的協議體系結構TCP/IP協議體系結構標準化的協議體系結構傳統的互聯網應用多媒體72.2ASimpleProtocolagentsinvolved:applicationscomputersnetworksexamplesofapplicationsincludefiletransferandelectronicmailtheseexecuteoncomputersthatsupportmultiplesimultaneousapplications8CommunicationLayerscommunicationtasksareorganizedintothreerelativelyindependentlayers: ApplicationlayerContainslogictosupportapplicationsTransportlayerprovidesreliabledatatransferNetworkaccesslayerconcernedwiththeexchangeofdata（應用層）（傳輸層）(網絡接入層)9NetworkAccessLayer網絡接入層coverstheexchangeofdatabetweenanendsystemandthenetworkthatitisattachedtoconcernedwithissueslike:destinationaddressprovisioninvokingspecificserviceslikepriorityaccessto&routingdataacrossanetworkfortwoendsystemsattachedtothesamenetwork10TransportLayer傳輸層11ApplicationLayer應用層containsthelogicneededtosupportuserapplicationsseparatemoduleisneededforeachtypeofapplication12ProtocolArchitectureandNetworks13ProtocolsinaSimplifiedArchitecture14Addressing尋址Twolevelsofaddressingareneeded:eachcomputeronthenetworkhasauniquenetworkaddresseachapplicationhasanaddressthatisuniquewiththatcomputer(SAPs)15ProtocolDataUnit(PDU)

協議數據單元thecombinationofdataandcontrolinformationisaprotocoldataunit(PDU)typicallycontrolinformationiscontainedinaPDUheadercontrolinformationisusedbythepeertransportprotocolatcomputerBheadersmayinclude:sourceport,destinationport,sequencenumber,anderror-detectioncode16NetworkAccessProtocolafterreceivingsegmentfromtransportlayer,thenetworkaccessprotocolmustrequesttransmissionoverthenetworkthenetworkaccessprotocolcreatesanetworkaccessPDU(packet)withcontrolinformationheaderincludes:sourcecomputeraddressdestinationcomputeraddressfacilitiesrequests17Contents為什么需要協議體系結構簡化的協議體系結構TCP/IP協議體系結構標準化的協議體系結構傳統的互聯網應用多媒體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思考題協議是什么？為什么需要協議？協議構成的基本要素是什么？協議體系結構為什么采用分層的方法？優缺點？三層簡單協議體系結構中，各層協議完成的功能？網絡系統中的兩級地址是？靠什么來傳遞對等層協議相關信息？協議體系結構的工作？TCP/IP協議包括哪五個部分？36Contents為什么需要協議體系結構簡化的協議體系結構TCP/IP協議體系結構標準化的協議體系結構傳統的互聯網應用多媒體37協議分層的理解請舉一日常生活中的例子來形象地描述該模型中各層的peer-to-peerprotocol（對等協議）和上下層之間的interface（接口）。北大學生張明給理工大學生李強寫信的例子

張明寫信李強讀信

封入信封拆開信封投入信箱從信箱中取信件收信分檢裝郵包開郵包選路投遞郵包送轉運站從轉運站取回郵包裝列車箱發運列車箱卸包送轉運站中文姓名地址目的地址目的站38張明給李強寫信的通信協議體系結構圖例張明（發送方）李強（接收方）2/1接口3/2接口4/3接口第4層第3層第2層第1層第2層對等協議第1層對等協議第3層對等協議第4層對等協議寫信讀信封信投信收信分檢裝包轉運郵包裝車卸車取回郵包投遞選路拆包拆信取信發車到站鐵軌（傳輸媒體）392.4StandardizedProtocolArchitectures40LayerSpecificStandards

特定層的標準41OSIStandardizationframeworkforstandardizationwasmotivatorlowerlayersareconcernedwithgreaterlevelsofdetailseachlayerprovidesservicestothenexthigherlayerthreekeyelements:ProtocolspecificationServicedefinitionAddressing42PrimitiveTypesREQUEST請求AprimitiveissuedbyaserviceusertoinvokesomeserviceandtopasstheparametersneededtospecifyfullytherequestedserviceINDICATION指示Aprimitiveissuedbyaserviceprovidereitherto:indicatethataprocedurehasbeeninvokedbythepeerserviceuserontheconnectionandtoprovidetheassociatedparameters,ornotifytheserviceuserofaprovider-initiatedactionRESPONSE

響應AprimitiveissuedbyaserviceusertoacknowledgeorcompletesomeprocedurepreviouslyinvokedbyanindicationtothatuserCONFIRM

證實Aprimitiveissuedbyaserviceprovidertoacknowledgeorcompletesomeprocedurepreviouslyinvokedbyarequestbytheserviceuser43ServicePrimitives（原語）andParametersdefineservicesbetweenadjacentlayersusing:primitivestospecifyfunctionperformedparameterstopassdataandcontrolinfo44Contents為什么需要協議體系結構簡化的協議體系結構TCP/IP協議體系結構標準化的協議體系結構傳統的互聯網應用多媒體45InternetApplicationsApplicationsthatoperateontopofTCPinclude:SMTPFTPSSHTCP46Contents為什么需要協議體系結構簡化的協議體系結構TCP/IP協議體系結構標準化的協議體系結構傳統的互聯網應用多媒體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彈性流量InelasticTraffic非彈性流量52MultimediaTechnologies53SummaryintroducedneedforprotocolarchitectureTCP/IPprotocolarchitectureprotocolarchitecturestandardizationmultimediaapplicationneeds協議的關鍵要素TCP/IP協議體系結構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