计算机网络双语论文

1计算机网络（双语）论文作者：孙然学号：0807240707院系：自动化工程学院专业：自动化题目：ThepaperofcomputernetworksandInternets指导者：韩晓菊评阅者：2010年12月21.Summury1.1Abstract：LANisasmallnetwork,usuallyarrangedinanorganizedofficearea.Rather,localareanetworksandwideareanetworkonlycorrespondstooneword,andthereisnostrictdefinition,anysmall-scalecommunicationsequipmentwithinafinitenumberofinterconnectedcommunicationsnetworkscanbecalledalocalareanetwork.Withtheextensiveapplicationofcommunicationtechnology,therapiddevelopmentoflocalareanetworkshasbecomeincreasinglymature,itisnotonlyabletomeetpeople'sneeds,butalsoconducivetotheaccelerationofthepaceofpeople'slivesandimprovethepeople'slivingstandards.LAN'sproductshavematured,aretoitssuperiorflexibilityandconvenienceofthenetworkapplicationsplayanincreasinglyimportantrole.1.2KeywordsLAN;switch;hub，IP1.3PartISomeknowledgeaboutLANLAN(LocalAreaNetwork,LAN)isinanareaconnectedbymultiplecomputersintocomputergroups.Withinaradiusofseveralkilometersgenerally.LANcanfilemanagement,applicationsoftware,sharing,printersharing,theWorkingGroup'sschedule,e-mailandfaxcommunicationservicesandotherfunctions.LANisclosed,andcanbecomposedoftwocomputerswithintheoffice,butalsobyacompanycomposedofthousandsofcomputersExternaldevicesanddatabases,linkingtoeachotherformofcomputercommunicationnetworks.Itcanbethroughdatacommunicationnetworksordedicateddatacircuits,andremoteLAN,connectedtoadatabaseorprocessingcentertoformawiderangeofinformationprocessingsystems.ReferredtoasLAN,isinanareaconnectedbymultiplecomputersintocomputergroups.Anareareferstothesameoffice,samebuilding,samecompanyandthesameschools,etc.,generallywithinaradiusofseveralkilometers.LANcanfilemanagement,applicationsoftware,sharing,printersharing,sharedscanner,theWorkingGroup'sschedule,e-mailandfax3communicationservicesandotherfunctions.LANisclosed,andcanbecomposedoftwocomputerswithintheoffice,butalsobyacompanycomposedofthousandsofcomputers.LANisusuallydistributedinalimitedgeographicrangeofnetworksystems,thegeneralgeographicalareacoveredbyonlyafewkilometers.DedicatedLANisverystrong,witharelativelystableandstandardizedtopology..1.3.1StarTopology:Thisisoneoftheoldestcommunicationsdesign,whichisrootedinthetelephoneexchangesystem.Becauseastar-shapednetworkresemblesthespokesofawheel,thecenterofastarnetworkisoftencalledahub.Atypicalhubconsistsofanelectronicdevicethatacceptsdatafromasendingcomputeranddeliversittotheappropriatedestination.Inpractice,starnetworksseldomhaveasymmetricshapeinwhichthehubislocatedanequaldistancefromallcomputers.Instead,ahuboftenresidesinalocationseparatefromthecomputersattachedtoit.1.3.2RingTopology:Anetworkthatusesaringtopologyarrangesforcomputerstobeconnectedinaclosedloop—-acableconnectsthefirstcomputertoasecondcomputer,anothercableconnectsthesecondcomputertoathird,andsoon,untilacableconnectsthefinalcomputerbacktothefirst.Thenameringarisesbecauseonecanimaginethecomputersandthecablesconnectingthemarrangedinacircle.Itisimportanttounderstandthatthering,likethestartopology,referstologicalconnectionsamongcomputers,notphysicalorientation–thecomputersand4connectionsinaringnetworkneednotbearrangedinacircle.Instead,thecablebetweenafloorofabuildingtoanother.Furthermore,ifonecomputerisfarfromothersinthering,thetwocablesthatconnectthedistantcomputermayfollowthesamephysicalpath.1.3.3BusTopology:Anetworkthatusesabustopologyusuallyconsistsofasingle,longcabletowhichcomputersattach.Anycomputerattachedtoabuscansendasignaldownthecable,andallcomputersreceivethesignal.Becauseallcomputersattachedtothecablecansenseanelectricalsignal,anycomputercansenddatatoanyothercomputer.Ofcourse,thecomputersattachedtoabusnetworkmustcoordinatetoensurethatonlyonecomputersendsasignalatanytimeorchaosresults.HereisoneexampleofBusNetwork:Ethernet.TheEthernetstandardspecifiesalldetails,includingtheformatofframesthatcomputerssendacrosstheether,thevoltagetobeused,andthemethodusedtomodulateasignal.Becauseitusesabustopology,Ethernetrequiresmultiplecomputerstoshareaccesstoasinglemedium.Asendertransmitsasignal,whichpropagatesfromthesendertowardbothendsofthecable.Asignalpropagatesfromthesendingcomputertobothendsofthesharedcable.Itisimportanttounderstandthatsharinginlocalareanetworkstechnologiesdoesnotmeanthatmultipleframesarebeingsentatthesametime.Instead,thesendingcomputerhasexclusiveuseoftheentirecableduringthetransmissionofagivenframe–othercomputersmustwait.Afteronecomputerfinishestransmittingoneframe,thesharedcablebecomesavailableforanothercomputertouse.Now,Iwillgiveasheetaboutthesethreekindsoftopologies.CapabilityStarTopologyRoundTopologyBusTopologyTransmissionSpeedLowHighestHigher5ControlMethodConcentrationDisperseConcentration/DisperseExpansionCapabilityLowLowHighThereasonformultipletopologiesisthateachtopologyhasadvantagesanddisadvantages.Aringtopologymakesiteasyforcomputerstocoordinateaccessandtodetectwhetherthenetworkisoperatingcorrectly.However,anentireringnetworkisdisabledifoneofthecablesiscut.Astartopologyhelpsprotectthenetworkfromdamagetoasinglecablebecauseeachcableconnectsonlyonemachine.Abusrequir