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ID:6696121
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页数:13页
时间:2018-01-22
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1、本科毕业论文英文翻译学院名称:计算机科学与通信工程学院专业班级:通信工程0501班学生姓名:指导教师姓名:指导教师职称:教授2009年3月RFC793-TransmissionControlProtocol2PHILOSOPHY2.1ElementsoftheInternetworkSystemTheinternetworkenvironmentconsistsofhostsconnectedtonetworkswhichareinturninterconnectedviagateways.Itisassum
2、edherethatthenetworksmaybeeitherlocalnetworks(e.g.,theETHERNET)orlargenetworks(e.g.,theARPANET),butinanycasearebasedonpacketswitchingtechnology.Theactiveagentsthatproduceandconsumemessagesareprocesses.Variouslevelsofprotocolsinthenetworks,thegateways,andthe
3、hostssupportaninterprocesscommunicationsystemthatprovidestwo-waydataflowonlogicalconnectionsbetweenprocessports.Thetermpacketisusedgenericallyheretomeanthedataofonetransactionbetweenahostanditsnetwork.Theformatofdatablocksexchangedwithintheanetworkwillgener
4、allynotbeofconcerntous.Hostsarecomputersattachedtoanetwork,andfromthecommunicationnetwork'spointofview,arethesourcesanddestinationsofpackets.Processesareviewedastheactiveelementsinhostcomputers(inaccordancewiththefairlycommondefinitionofaprocessasaprogramin
5、execution).EventerminalsandfilesorotherI/Odevicesareviewedascommunicatingwitheachotherthroughtheuseofprocesses.Thus,allcommunicationisviewedasinter-processcommunication.Sinceaprocessmayneedtodistinguishamongseveralcommunicationstreamsbetweenitselfandanother
6、process(orprocesses),weimaginethateachprocessmayhaveanumberofportsthroughwhichitcommunicateswiththeportsofotherprocesses.2.2ModelofOperationProcessestransmitdatabycallingontheTCPandpassingbuffersofdataasarguments.TheTCPpackagesthedatafromthesebuffersintoseg
7、mentsandcallsontheinternetmoduletotransmiteachsegmenttothedestinationTCP.ThereceivingTCPplacesthedatafromasegmentintothereceivinguser'sbufferandnotifiesthereceivinguser.TheTCPsincludecontrolinformationinthesegmentswhichtheyusetoensurereliableordereddatatran
8、smission.ThemodelofinternetcommunicationisthatthereisaninternetprotocolmoduleassociatedwitheachTCPwhichprovidesaninterfacetothelocalnetwork.ThisinternetmodulepackagesTCPsegmentsinsideinternetdatagramsa
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