實(shí)用IT英語(yǔ)（第4版） 課件 Unit 7 Computer Networks

ComputerNetworksUnit7實(shí)用IT英語(yǔ)（第4版）INFORMATIONCommunicationsTECHNOLOGYInthisunit,wearefocusingonthefollowingissues.LAN;WAN;peer-to-peer;protocol;wirelessnetworking;networktopology;TCP/IP;Gridcomputing;USBOutlineComputernetworksanditsapplication.LAN/WANandwirelessnetworking.Introductiontonetworkcables.HowtoconfigureyourIPaddress.Howtosignupforahotmailmailbox.ProfessionalTerminologyDialogue:HowComputersCommunicatewithEachOtherSection

2ReadingTextA:ComputerNetworkingTextB:IntroductiontoNetworkTypesTextC:IntroductiontoNetworkCablesOccupationalTips:HowtoConfigureYourIPAddressClassActivities:SignupforaHotmailMailboxCONTENTSSection

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4Dialogue:HowComputersCommunicatewithEachOther01Directions:Readthefollowingdialogueinpairsandtalkabouthowcomputerscommunicatewitheachother?Situation:JohnNewtonisagraduateofCollegePark.EricKingisanassociateprofessorinthecollege.JohnisconsultingProfessorKingwhattolearn.JohnNewton:Iwouldliketolearncomputertechnology.Whichareasaremoreimportant?EricKing:Manyofthemareworthlearning.But,datacommunicationisthemostimportantbranchofinformationtechnology.JohnNewton:Whydoyousaythat?EricKing:Todaynobusinesscanbesuccessfulwithouttheproperimplementationofcommunicationsystems.Computerscantalktoeachothertosendandreceivevoice,videoanddatasignals.JohnNewton:Well,Ijustwonderhowcomputerscancommunicatewitheachother.Dialogue:HowComputersCommunicatewithEachOther01EricKing:Therearesomepredefinedrules,protocols,standardsanddevicesthatareinvolvedintheoverallcommunicationprocess.JohnNewton:Protocols?EricKing:Yes,computersmustunderstandthecommonlanguagesknownasprotocols,suchasTCP/IP.JohnNewton:IthinkI’veheardtheterm,butstilldonotquiteunderstand.EricKing:Justliketwobabiescannottalk,twopeopleinaconversationmustunderstandthesamelanguage.YoucanthinkofTCP/IPasthislanguage.JohnNewton:Thenhowtoteachcomputerstolearnthelanguage?EricKing:TCP/IPmustbeproperlyinstalledandconfiguredoneverycomputer.Atthesametime,everycomputermustpossessaLANcardwithanupdateddriverandpreciseconfiguration.JohnNewton:Isthatall?EricKing:No,therearedifferenttypesofprotocolssuchasTCP/IP,IPX/SPX,NetBEUIandNetBIOS.There’snowaytoclearlyexplainthisinaword.JohnNewton:Thatsoundsreallyfascinating!Well,I’vedecidedtochoosethisfieldtostudy.Dialogue:HowComputersCommunicatewithEachOther01Notesprotocol01TCP/IPIPX/SPXNetBEUINetBIOS02030405網(wǎng)絡(luò)的基本輸入輸出系統(tǒng)協(xié)議（信息交換）協(xié)議傳輸控制協(xié)議/網(wǎng)絡(luò)協(xié)議Internet分組交換/順序分組交換協(xié)議NetBIOS用戶擴(kuò)展接口協(xié)議Dialogue:HowComputersCommunicatewithEachOtherSection

2ReadingTextA:ComputerNetworkingTextB:IntroductiontoNetworkTypesTextC:IntroductiontoNetworkCablesOccupationalTips:HowtoConfigureYourIPAddressClassActivities:SignupforaHotmailMailboxCONTENTSSection

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4TextA:ComputerNetworking01Intheworldofcomputers,networkingisthepracticeoflinkingtwoormorecomputingdevicestogetherforthepurposeofsharingdata.Networksarebuiltwithamixofcomputerhardwareandcomputersoftware.AreaNetworksNetworkscanbecategorizedinseveraldifferentways.Oneapproachdefinesthetypeofnetworkaccordingtothegeographicareaitspans.Localareanetworks(LANs),forexample,typicallyreachacrossasinglehome,whereaswideareanetworks(WANs),reachacrosscities,states,orevenacrosstheworld.TheInternetistheworld’slargestpublicWAN.NetworkDesignComputernetworksalsodifferintheirdesign.Thetwotypesofhigh-levelnetworkdesignarecalledclient-serverandpeer-to-peer(Figure7-1).Client-servernetworksfeaturecentralizedservercomputersthatstoreemail,Webpages,filesorapplications.Onapeer-to_x0002_peernetwork,conversely,allcomputerstendtosupportthesamefunctions.Client-servernetworksaremuchmorecommoninbusinessandpeer-to-peernetworksmuchmorecommoninhomes.TextA:ComputerNetworking01(a)Client-servernetworkAnetworktopology(Figure7-2)representsitslayoutorstructurefromthepointofviewofdataflow.Inso-calledbusnetworks,forexample,allofthecomputersshareandcommunicateacrossonecommonconduit,whereasinastarnetwork,alldataflowsthroughonecentralizeddevice.Commontypesofnetworktopologiesincludebus,star,ringandesh.(b)Peer-to-peernetworkFigure7-1NetworkDesignTextA:ComputerNetworking01NetworkProtocolsInnetworking,thecommunicationlanguageusedbycomputerdevicesiscalledtheprotocol.Yetanotherwaytoclassifycomputernetworksisbythesetofprotocolstheysupport.Networksoftenimplementmultipleprotocolstosupportspecificapplications.PopularprotocolsincludeTCP/IP,themostcommonprotocolfoundontheInternetandinhomenetworks.Figure7-2TypesofNetworkTopologiesTextA:ComputerNetworking01WiredNetworkingVS.WirelessNetworkingManyofthesamenetworkprotocols,likeTCP/IP,workinbothwiredandwirelessnetworks.NetworkswithEthernetcablespredominatedinbusinesses,schools,andhomesforseveraldecades.Recently,however,wirelessnetworkingalternativeshaveemergedasthepremiertechnologyforbuildingnewcomputernetworks.Wirelessnetworksutilizeradiowavesand/ormicrowavestomaintaincommunicationchannelsbetweencomputers.Wirelessnetworkingisamoremodernalternativetowirednetworkingthatreliesoncopperand/orfiberopticcablingbetweennetworkdevices.Awirelessnetworkoffersadvantagesanddisadvantagescomparedtoawirednetwork.Advantagesofwirelessincludemobilityandeliminationofunsightlycables.Disadvantagesofwirelessincludethepotentialforradiointerferenceduetoweather,otherwirelessdevices,orobstructionslikewalls.Wirelessisrapidlygaininginpopularityforbothhomeandbusinessnetworking.Wirelesstechnologycontinuestoimprove,andthecostofwirelessproductscontinuestodecrease.Popularwirelesslocalareanetworking(WLAN)productsconformtothe802.11“Wi-Fi”standards.Thegearapersonneedstobuildwirelessnetworksincludesnetworkadapters(NICs),accesspoints(APs),androuters.TextA:ComputerNetworking01network01hardwaresoftwaregeographicLAN02030405n.局域網(wǎng)（LocalAreaNetwork）n.網(wǎng)絡(luò)n.硬件n.軟件n.地理NewWords&ExpressionsWAN06n.廣域網(wǎng)（WideAreaNetwork）0708091011client-serverpeer-to-peernetworkdataflowbusn.［計(jì)］總線n.客戶端-服務(wù)器n.對(duì)等網(wǎng)n.數(shù)據(jù)流wirelessn.無(wú)線TextA:ComputerNetworking01Ⅰ.Answerthefollowingquestionsaccordingtothetext.Exercises1.Whatiscomputernetworking?2.Accordingtothegeographicarea,howcannetworksbecategorized?3.WhatisthemostcommonprotocolfoundontheInternetandinhomenetworks?Ⅱ.Decidewhetherthefollowingstatementsaretrueorfalse.()1.Localareanetworks(LANs),forexample,typicallyreachacrossasinglehome.()2.TheInternetistheworld’slargestpublicLAN.()3.Manyofthesamenetworkprotocols,likeTCP/IP,workonlyinwirelessnetworks.()4.Innetworking,thecommunicationlanguageusedbycomputerdevicesiscalledtheprotocol.()5.Commontypesofnetworktopologiesincludebus,star,ringandmesh.TFFTTTextB:IntroductiontoNetworkTypes01Onewaytocategorizethedifferenttypesofcomputernetworkdesignsisbytheirscopeorscale.Forhistoricalreasons,thenetworkingindustryreferstonearlyeverytypeofdesignassomekindofareanetwork.Commonexamplesofareanetworktypesare:LAN-LocalAreaNetwork.?WLAN-WirelessLocalAreaNetwork.?WAN-WideAreaNetwork.?MAN-MetropolitanAreaNetwork.?SAN-StorageAreaNetwork,SystemAreaNetwork,ServerAreaNetwork,orsometimesSmallAreaNetwork.?CAN-CampusAreaNetwork,ControllerAreaNetwork,orsometimesClusterAreaNetwork.PAN-PersonalAreaNetwork.?DAN-DeskAreaNetwork.LANandWANweretheoriginalcategoriesofareanetworks,whiletheothershavegraduallyemergedovermanyyearsoftechnologyevolution.TextB:IntroductiontoNetworkTypes01LAN-LocalAreaNetworkAlocalareanetwork(LAN)suppliesnetworkingcapabilitytoagroupofcomputersincloseproximitytoeachothersuchasinanofficebuilding,aschool,orahome.ALANisusefulforsharingresourceslikefiles,printers,gamesorotherapplications.ALANinturnoftenconnectstootherLANs,andtotheInternetorotherWANs.MostlocalareanetworksarebuiltwithrelativelyinexpensivehardwaresuchasEthernetcables,networkadapters,andhubs.WirelessLANandothermoreadvancedLANhardwareoptionsalsoexist.Specializedoperatingsystemsoftwaremaybeusedtoconfigurealocalareanetwork.Forexample,mostflavorsofMicrosoftWindowsprovideasoftwarepackagecalledInternetConnectionSharing(ICS)thatsupportscontrolledaccesstoLANresources.ThetermLANpartyreferstoamultiplayergamingeventwhereparticipantsbringtheirowncomputersandbuildatemporaryLAN.ThemostcommontypeoflocalareanetworkisanEthernetLAN.ThesmallesthomeLANcanhaveexactlytwocomputers;alargeLANcanaccommodatemanythousandsofcomputers.ManyLANsaredividedintologicalgroupscalledsubnets.AnInternetProtocol(IP)“ClassA”LANcanintheoryaccommodatemorethan16milliondevicesorganizedintosubnets.TextB:IntroductiontoNetworkTypes01WAN-WideAreaNetworkAsthetermimplies,aWANspansalargephysicaldistance.TheInternetisthelargestWAN,spanningtheEarth.AWANisageographically-dispersedcollectionofLANs.AnetworkdevicecalledarouterconnectsLANstoaWAN.InIPnetworking,theroutermaintainsbothaLANaddressandaWANaddress.AWANdiffersfromaLANinseveralimportantways.MostWANs(liketheInternet)arenotownedbyanyoneorganizationbutratherexistundercollectiveordistributedownershipandmanagement.WANstendtousetechnologylikeATM,FrameRelayandX.25forconnectivityoverthelongerdistances.LANVS.WANSeeTable7-1.DimensionsLANsWANsDataTransferratesLANshaveahighdatatransferrateWANshavealowerdatatransferrateascomparedtoLANsTechnologyLANstendtousecertainconnectivitytechnologies,primarilyEthernetandTokenRingWANstendtousetechnologylikeMPLS,ATM,FrameRelayandX.25forconnectivityoverthelongerdistancesTextB:IntroductiontoNetworkTypes01DimensionsLANsWANsConnectionOneLANcanbeconnectedtootherLANsoveranydistanceviatelephonelinesandradiowavesComputersconnectedtoawide-areanetworkareoftenconnectedthroughpublicnetworks,suchasthetelephonesystem.TheycanalsobeconnectedthroughleasedlinesorsatellitesSpeedhighspeed(1000Mbit/s)lowerspeed(150Mbit/s)MaintenanceCostsBecauseitcoversarelativelysmallgeographicalarea,LANiseasiertomaintainatrelativelylowcostsMaintainingWANisdifficultbecauseofitswidergeographicalcoverageandhighermaintenancecostsFaultToleranceLANstendtohavefewerproblemsassociatedwiththem,asthereareasmalleramountofsystemstodealwithWANstendtobelessfaulttolerant,asitconsistsofalargeamountofsystemsandthereisaloweramountoffaulttoleranceExampleNetworkinanorganizationcanbeaLANInternetisthebestexampleofaWANGeographicalSpreadHaveasmallgeographicalrangeanddonotneedanyleasedtelecommunicationlinesHavealargegeographicalrangegenerallyspreadingacrossboundariesandneedleasedtelecommunicationlinesTextB:IntroductiontoNetworkTypes01DimensionsLANsWANsSet-upCostsIfthereisaneedtosetupacoupleofextradevicesonthenetwork,itisnotveryexpensivetodothatInthiscase,sincenetworksinremoteareashavetobeconnectedhencetheset-upcostsarehigher.However,WANsusingpublicnetworkscanbesetupverycheaply,justsoftware(VPNetc.)OwnershipTypicallyowned,controlled,andmanagedbyasinglepersonororganizationWANs(liketheInternet)arenotownedbyanyoneorganizationbutratherexistundercollectiveordistributedownershipandmanagementoverlongdistancesDefinitionLAN(LocalAreaNetwork)isacomputernetworkcoveringasmallgeographicarea,likeahome,office,schools,orgroupofbuildingsWAN(WideAreaNetwork)isacomputernetworkthatcoversabroadarea(e.g.,anynetworkwhosecommunicationslinkscrossmetropolitan,regional,ornationalboundariesoveralongdistanceComponentslayer2deviceslikeswitches,bridges.layer1deviceslikehubs,repeatersLayers3devicesRouters,Multi-layerSwitchesandTechnologyspecificdeviceslikeATMorFrame-relaySwitchesetc.DataTransmissionErrorExperiencesfewerdatatransmissionerrorsExperiencesmoredatatransmissionerrorsascomparedtoLANTextB:IntroductiontoNetworkTypes01WLAN01MANSANCANPAN02030405abbr.個(gè)人區(qū)域網(wǎng)絡(luò)（PersonalAreaNetwork）abbr.無(wú)線局域網(wǎng)（WirelessLocalAreaNetwork）abbr.城域網(wǎng)（MetropolitanAreaNetwork）abbr.存儲(chǔ)區(qū)域網(wǎng)絡(luò)（StorageAreaNetwork）abbr.校園局域網(wǎng)（CampusAreaNetwork）NewWords&ExpressionsDAN06abbr.臺(tái)區(qū)網(wǎng)絡(luò)（DeskAreaNetwork）0708IPICSabbr.互聯(lián)網(wǎng)協(xié)議（InternetProtocol）abbr.Internet連接共享（InternetConnectionSharing）TextB:IntroductiontoNetworkTypes01Ⅰ.Fillintheblanksaccordingtothetext.Exercises1.Onewaytocategorizethedifferenttypesofcomputernetworkdesignsisbytheir_______or_______.2._______________________suppliesnetworkingcapabilitytoagroupofcomputersincloseproximitytoeachother.3.Theterm____________referstoamultiplayergamingeventwhereparticipantsbringtheirowncomputersandbuildatemporaryLAN.4.ManyLANsaredividedintologicalgroupscalled_______.5.Most_______arenotownedbyanyoneorganizationbutratherexistundercollectiveordistributedownershipandmanagement.scopescaleAlocalareanetwork(LAN)LANpartysubnetsWANsTextB:IntroductiontoNetworkTypes01Ⅱ.Decidewhetherthefollowingstatementsaretrueorfalse.Exercises()1.ALANinturnoftendoesnotconnecttootherLANs,buttotheInternetorotherWANs.()2.MostlocalareanetworksarebuiltwithrelativelyexpensivehardwaresuchasEthernetcables,networkadapters,andhubs.()3.WANstendtousetechnologylikeATM,FrameRelayandX.25forconnectivityoverthelongerdistances.()4.LANandWANweretheoriginalcategoriesofareanetworks,whiletheothershavegraduallyemergedovermanyyearsoftechnologyevolution.()5.WAN(WideAreaNetwork)isacomputernetworkthatcoversabroadarea.FFTTTTextC:IntroductiontoNetworkCables01Eventhoughtherehavebeenadvancesinwirelesstechnologies,manycomputernetworksinthe21stcenturyrelyoncablesasthephysicalmediumthatdevicesusetotransferdata.Severalstandardtypesofnetworkcablesexist,eachdesignedforspecificpurposes.CoaxialCablesInventedinthe1880s,coaxialcable(alsocalledcoax)wasbestknownasthekindofcablethatconnectedtelevisionsetstohomeantennas.Coaxialcableisalsoastandardfor10Mbit/sEthernetcables.When10Mbit/sEthernetwasmostpopular,duringthe1980sandearly1990s,networkstypicallyusedoneoftwokindsofcoaxcable—thinnet(10BASE2standard)orthicknet(10BASE5).Thesecablesconsistofaninnercopperwireofvaryingthicknesssurroundedbyinsulationandanothershielding.Theirstiffnesscausednetworkadministratorsdifficultywheninstallingandmaintainingthinnetandthicknet.TwistedPairCablesTwistedpairemergedduringthe1990sastheleadingcablingstandardforEthernet,startingwith10Mbit/s(10BASE-T,alsoknownasCategory3orCat3),laterfollowedbyimprovedversionsfor100Mbit/s(100BASE-TX,Cat5,andCat5e)andsuccessivelyhigherspeedsupto10Gbit/s(10GBASE-T).Ethernettwistedpaircablescontainuptoeightwireswoundtogetherinpairstominimizeelectromagneticinterference.TextC:IntroductiontoNetworkCables01FiberOpticsInsteadofinsulatedmetalwirestransmittingelectricalsignals,fiberopticnetworkcablesusestrandsofglassandpulsesoflight.Thesenetworkcablesarebendabledespitebeingmadeofglass.Theyhaveprovenespeciallyusefulinwideareanetwork(WAN)installationswherelong-distanceundergroundoroutdoorcablerunsarerequiredandalsoinofficebuildingswhereahighvolumeofcommunicationtrafficiscommon.Twoprimarytypesoffiberopticcableindustrystandardsaredefined—single-mode(100BaseBXstandard)andmultimode(100BaseSXstandard).Long-distancetelecommunicationsnetworkscommonlyusesingle-modeforitsrelativelyhigherbandwidthcapacity,whilelocalnetworkstypicallyusemultimodeduetoitslowercost.USBCablesMostUniversalSerialBus(USB)cablesconnectacomputerwithaperipheraldevice(suchasakeyboardormouse)ratherthantoanothercomputer.However,specialnetworkadapters(sometimescalleddongles)connectanEthernetcabletoaUSBportindirectly.USBcablesfeaturetwisted-pairwiring.Twoprimarytypesoftwistedpaircableindustrystandardshavebeendefined:UnshieldedTwistedPair(UTP)andShieldedTwistedPair(STP).ModernEthernetcablesuseUTPwiringduetoitslowercost,whileSTPcablingcanbefoundinothertypesofnetworkssuchasFiberDistributedDataInterface(FDDI).TextC:IntroductiontoNetworkCables01NewWords&Expressions010203coaxialcabletwistedpaircableUTPSTPFDDIfiberopticUSB同軸電纜雙絞電纜abbr.無(wú)屏蔽雙絞線（UnshieldedTwistedPair）abbr.屏蔽雙絞線（ShieldedTwistedPair）abbr.光纖分布式數(shù)據(jù)接口（FiberDistributed

DataInterface）光纖abbr.通用串行總線（UniversalSerialBus）04050607TextC:IntroductiontoNetworkCables01Ⅰ.Fillintheblanksaccordingtothetext.Exercises1.Cablesarethephysicalmediumthatdevicesuseto_______data.2.ModernEthernetcablesuse_______wiringduetoitslowercost.3.Insteadofinsulatedmetalwirestransmittingelectricalsignals,_______networkcablesusestrandsofglassandpulsesoflight.4.Long-distancetelecommunicationsnetworkscommonlyuse_______foritsrelativelyhigherbandwidthcapacity5.Most_______(USB)cablesconnectacomputerwithaperipheraldevice(suchasakeyboardormouse)ratherthantoanothercomputer.TextC:IntroductiontoNetworkCables01Ⅱ.Decidewhetherthefollowingstatementsaretrueorfalse.Exercises()1.Inventedinthe1880s,twistedpaircableswerebestknownasthekindofcablethatconnectedtelevisionsetstohomeantennas.()2.Twistedpairemergedduringthe1990sastheleadingcablingstandardforEthernet,startingwith100Mbit/s.()3.ModernEthernetcablesuseSTPwiringduetoitslowercost.()4.Twoprimarytypesoffiberopticcableindustrystandardsaredefined—single_x0002_modeandmultimode.()5.Specialnetworkadapters(sometimescalleddongles)connectanEthernetcabletoaUSBportdirectly.TTTFFDialogue:HowComputersCommunicatewithEachOtherSection

2ReadingTextA:ComputerNetworkingTextB:IntroductiontoNetworkTypesTextC:IntroductiontoNetworkCablesOccupationalTips:HowtoConfigureYourIPAddressClassActivities:SignupforaHotmailMailboxCONTENTSSection

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4OccupationalTips:HowtoConfigureYourIPAddress01Directions:ReadthetipsonhowtoconfigureyourIPaddress.HowtoConfigureYourStaticIPAddressByLeoA.NotenboomContributorWhenyougotothenewcompanyfirstday,youwillbeassignedanewcomputerandanIPaddress.Onceyou’vebeenassignedastaticIPaddressyou’llneedtoconfigurethenetwork-connecteddevicemanuallytouseit,solet’sseehow.IfyourcomputerisconnecteddirectlytotheInternet,meaningit’snotbehindarouterorafirewall,it’sactuallyprettysimple.InControlPanel,NetworkConnections,findthenetworkconnectionthatrepresentsyourconnectiontotheInternet.Mostoftenit’slabeledsimplyLocalArea

Connection.RightclickonthatandselectProperties(Figure7-3).NowclickontheInternetProtocol(TCP/IP)iteminthelist(youmayhavetoscrolldownwithinthelisttofindit).OccupationalTips:HowtoConfigureYourIPAddress01Figure7-3Ethernet0PropertiesNowclickonthepropertiesbutton.AdefaultconfigurationwillhavebothObtainanIPaddressautomatically,andObtainDNSserveraddressautomaticallyselected.ClickonUsethefollowingIPaddressandentertheIPaddress(Figure7-4),subnetmask,anddefaultgatewayinformationthatyourISPshouldhavegivenyou.(Iftheydidnotgiveyouallthree,askthem.)Figure7-4EntertheIPAddressOccupationalTips:HowtoConfigureYourIPAddress01InmostcasestheywillalsogiveyouIPaddressesfortheDNSserversyoushoulduse.ClickonUsethefollowingDNSserveraddressesandenterthatinformationaswell.That’sit.Onceyou“OK”yourwayoutofthoseconfigurationdialogs,yourcomputershouldnowrespondtoitsassignedIPaddress.IntheStartmenu,clicktheRun,type“cmd”.Inthisprogram,type“ipconfig”.Then,checkyourIPaddress.Dialogue:HowComputersCommunicatewithEachOtherSection

2ReadingTextA:ComputerNetworkingTextB:IntroductiontoNetworkTypesTextC:IntroductiontoNetworkCablesOccupationalTips:HowtoConfigureYourIPAddressClassActivities:SignupforaHotmailMailboxCONTENTSSection

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4ClassActivities:SignupforaHotmailMailbox01Directions:

Hotmailisanemailservicewhichwasbroughtoutveryearlyandusedbylotsofpeople.Nowadays,withHotmailorOutlookaccount,youcanuseallemailservicesandofcourse,otherservicesofMicrosoft.FollowthefollowingstepsandyouwillcreateaHotmailaccountbyyourself!OpenFirefoxorGoogleChromeorotherbrowsers,thenclickheretogotoHotmailsignupform.Fil