Internet的发展历史 中英文

THEHISTORYOFTHEINTERNETTheBeginning-ARPAnetTheInternetstartedasaprojectbytheUSgovernment.Theobjectoftheprojectwastocreateameansofcommunicationsbetweenlongdistancepoints,intheeventofanationwideemergencyor,morespecifically,nuclearwar.TheprojectwascalledARPAnet,anditiswhattheInternetstartedas.Fundedspecificallyformilitarycommunication,theengineersresponsibleforARPANethadnoideaofthepossibilitiesofanInternet.Bydefinition,an'Internet'isfourormorecomputersconnectedbyanetwork.ARPAnetachieveditsnetworkbyusingaprotocolcalledTCP/IP.Thebasicsaroundthisprotocolwasthatifinformationsentoveranetworkfailedtogetthroughononeroute,itwouldfindanotherroutetoworkwith,aswellasestablishingameansforonecomputertotalktoanothercomputer,regardlessofwhetheritwasaPCoraMacintosh.Bythe80'sARPAnet,justyearsawayfrombecomingthemorewellknownInternet,had200computers.TheDefenseDepartment,satisfiedwithARPAnetsresults,decidedtofullyadoptitintoservice,andconnectedmanymilitarycomputersandresourcesintothenetwork.ARPAnetthenhad562computersonitsnetwork.Bytheyear1984,ithadover1000computersonitsnetwork.In1986ARPAnet(supposedly)shutdown,butonlytheorganizationshutdown,andtheexistingnetworksstillexistedbetweenthemorethan1000computers.ItshutdownduetoafailiedlinkupwithNSF,whowantedtoconnectits5countywidesupercomputersintoARPAnet.WiththefundingofNSF,newhighspeedlinesweresuccessfullyinstalledatlinespeedsof56k(anormalmodemnowadays)throughtelephonelinesin1988.Bythattime,therewere28,174computersonthe(bythendecided)Internet.In1989therewere80,000computersonit.By1989,therewere290,000.Anothernetworkwasbuilttosupporttheincrediblenumberofpeoplejoining.Itwasconstructedin1992.Today-TheInternetToday,theInternethasbecomeoneofthemostimportanttechnologicaladvancementsinthehistoryofhumanity.Everyonewantstoget'online'toexperiencethewealthofinformationoftheInternet.MillionsofpeoplenowusetheInternet,andit'spredictedthatbytheyear2003everysinglepersonontheplanetwillhaveInternetaccess.TheInternethastrulybecomeawayoflifeinourtimeandera,andisevolvingsoquicklyitshardtodeterminewhereitwillgonext,ascomputerandnetworktechnologyimproveeveryday.HOWITWORKS:It'sastandardthing.PeopleusingtheInternet.Shopping,playinggames,conversinginvirtualInternetenvironments.TheInternetisnota'thing'itself.TheInternetcannotjustcrash.Itfunctionsthesamewayasthetelephonesystem,onlythereisnoInternetcompanythatrunstheInternet.TheInternetisacollectionofmillioinsofcomputersthatareallconnectedtoeachother,orhavethemeanstoconnecttoeachother.TheInternetisjustlikeanofficenetwork,onlyithasmillionsofcomputersconnectedtoit.ThemainthingabouthowtheInternetworksiscommunication.HowdoesacomputerinHoustonknowhowtoaccessdataonacomputerinTokyotoviewawebpage?Internetcommunication,communicationamongcomputersconnectedtotheInternet,isbasedonalanguage.ThislanguageiscalledTCP/IP.TCP/IPestablishesalanguageforacomputertoaccessandtransmitdataovertheInternetsystem.ButTCP/IPassumesthatthereisaphysicalconnecetionbetweenonecomputerandanother.Thisisnotusuallythecase.TherewouldhavetobeanetworkwirethatwenttoeverycomputerconnectedtotheInternet,butthatwouldmaketheInternetimpossibletoaccess.Thephysicalconnectionthatisrequireedisestablishedbywayofmodems,phonelines,andothermodemcableconnections(likecablemodemsorDSL).Modemsoncomputersreadandtransmitdataoverestablishedlines,whichcouldbephonelinesordatalines.Theactualhardcoreconnectionsareestablishedamongcomputerscalledrouters.Arouterisacomputerthatservesasatrafficcontrollerforinformation.Toexplainthisbetter,let'slookathowastandardcomputermightviewawebpage.1.Theuser'scomputerdialsintoanInternetServiceProvider(ISP).TheISPmightinturnbeconnectedtoanotherISP,orastraightconnectionintotheInternetbackbone.2.TheuserlaunchesawebbrowserlikeNetscapeorInternetExplorerandtypesinaninternetlocationtogoto.3.Here'swherethetrickypartcomesin.First,thecomputersendsdataaboutit'sdatarequesttoarouter.Arouterisaveryhighspeedpowerfulcomputerrunningspecialsoftware.Thecollectionofroutersintheworldmakewhatiscalledabackbone,onwhichallthedataontheInternetistransferred.Thebackbonepresentlyoperatesataspeedofseveralgigabytesper-second.Suchaspeedcomparedtoanormalmodemislikecomparingtheheatofthesuntotheheatofanice-cube.Routershandledatathatisgoingbackandforth.Arouterputssmallchunksofdataintopackagescalledpackets,whichfunctionsimilarlytoenvelopes.So,whentherequestforthewebpagegoesthrough,itusesTCP/IPprotocolstotelltherouterwhattodowiththedata,whereit'sgoing,andoverallwheretheuserwantstogo.4.Theroutersendsthesepacketstootherrouters,eventuallyleadingtothetargetcomputer.It'slikewhisperdownthelane(onlytheinformationremainsintact).5.Whentheinformationreachesthetargetwebserver,thewebserverthenbeginstosendthewebpageback.Awebserveristhecomputerwherethewebpageisstoredthatisrunningaprogramthathandlesrequestsforthewebpageandsendsthewebpagetowhoeverwantstoseeit.6.Thewebpageisputinpackets,sentthroughrouters,andarriveattheuserscomputerwheretheusercanviewthewebpageonceitisassembled.Thepacketswhichcontainthedataalsocontainspecialinformationthatletsroutersan