网络环境与实现翻译的

E-LearningenvironmentnetworkWiththerapiddevelopmentofnetworktechnology,especiallydigitalcampusandtheconstructionofeducationalinformationneedsofthecampusnetworkhavebecomeincreasinglydemanding.Intermsofspeed,campusnetworkbackbonespeedincreasefromthefirst100Mbpsto10,000Mbps(10Gbps).Intheagreement,frompasttoupgradetotheIPv4IPv6.Inthesegmenthasalsobeenaqualitativebreakthrough:fromtheearlydevelopmentofthesharedmediumlocalareanetworktothecurrentswitchedLAN.SwitchedLANtechnologyenablesbandwidthofdedicatedusersasopposedtogreatlyimprovetheefficiencyoflocalareanetworktransmission.Inaddition,suchasthebroadbandintelligentnetwork,intelligentopticalnetworking,opticalfibercommunicationnetworkandsoftswitchtechnology,newnetworktechnologiesareemerging.Weregiventhefollowingset1Multi-layerswitchingtechnologyparknetworknetwork.Convergencelayergenerallyfarawayfromthenetworkcenter,theneedfordozensofbuildingsafewblocksoraccessswitchconvergence,foraregionalnetworking.Accesslayergenerallylocatedwithinabuilding,orthefloorforGailoucomputerterminalnetwork.Asthemorecomplexthestructureofthecampusnetwork,themanagementbemorenumberofcomputers,inordertobettermanagethenetwork,improvenetworkefficiency,thelayeredswitchingtechnologyinvolved.Amongthem,thethirdlayerswitchingtechnologyisoperationalinthethirdlayernetworkprotocolisaroutingdeviceandcanbeplayedtounderstandtheroleoftheroutingdecision;fast,almosttothesecondtierexchangerate.Here,wediscussanexampleofaparkshouldbeconsideredinnetworkdesignandnetworkswitchingelements.Thecurrentnetworkarchitecturewithlayeredstructureare:corelayer,convergencelayerandaccesslayer.Fromthenetworkprotocollevelcanbedividedintothefirstlayer,secondlayer,thirdlayer....Thestructureofthenetworksystem,thecorelayerinthenetworkengineroom,responsibleforthemanagementoftheentirecampusnetwork.Convergencelayergenerallyfarawayfromthenetworkcenter,theneedfordozensofbuildingsafewblocksoraccessswitchconvergence,foraregionalnetworking.Accesslayergenerallylocatedwithinabuilding,orthefloorforGailoucomputerterminalnetwork.Asthemorecomplexthestructureofthecampusnetwork,themanagementbemorenumberofcomputers,inordertobettermanagethenetwork,improvenetworkefficiency,thelayeredswitchingtechnologyinvolved.Amongthem,thethirdlayerswitchingtechnologyisoperationalinthethirdlayernetworkprotocolisaroutingdeviceandcanbeplayedtounderstandtheroleoftheroutingdecision;fast,almosttothesecondtierexchangerate.1.1FlatBridgeNetworkThefirstparkisconsideredthesingleLANinthenumberofnewusersaddedtotheformation.ThisLANisanetworkdeviceconnectedthroughthephysicalorlogicallineswithanetwork.Insuchanetwork,allnetworkdevicestosharethe10Mbpshalf-duplexEthernetbandwidthavailable.Atthistime,thewholenetworkisaconflictdomain,becauseallnetworkdevicescanlistentothenetworktotransmitdatapacketswillhaveconflicts,andthereforetheintroductionofCSMA/CDcollisiondetectionmechanismtoplanthenetworkdatatransmission.Whenaconflictdomaindatatransferhasbecomeverycrowded,usuallyweshouldaddabridge.Bridgeisastore-forwardtypeofdatapacketswitches,whichthewholenetworkintoseveralcollisiondomains,toreducepacketcollisions,increasethetransmissionefficiency.Bridgewillnotendtheisolationnetworkbroadcast,multicast,andmulticastdata,thatis,allbridgenetworksthroughoutthecampusnetworkisasinglebroadcastdomain.Thisposesaproblemofdatacircuits,applicationoftheapplicationofSTPSpanningTreeProtocolcansuccessfullypreventtheloop.Intheory,thesizeofthedatabroadcastbythebroadcastdomainsizelimit,infact,managementofabridgestructureofthecampusnetworkwillbeexpandedasthenetworkbecomesmoreandmoredifficult,aworkstationmaycausefailureoftheentirenetworkparalysis.Whenthedesignofthebridgenet,eachbridgesegmentisequivalenttoaworkinggroup,workgroupserverandclientasbeinginthesamesegment,themajorityofdatatransmissioninthelocalsegment,whichisfollowthe80/20principle。1.2AddressingcapacityandexpansioncapacityRouterisusedtobuildapacketswitchnetwork,responsibleforthedifferenttransferdatabetweenbroadcastdomains.Routerisbasedonnetworkaddressratherthanthephysicaladdresstoforwardpackets.ScalabilityoftheInternetnetworkisbetterthanthebridge,becausethenetworkaddressoftheroutercanbesummedupinordertoestimateabesttransmissionpath,typicallybetweenrouters,suchasOSPF,EIGRProutingprotocolliketoexchangeroutinginformation.ComparedwiththeSTP,routingprotocolshavethefollowingcharacteristics:(1)thecostcanbeseveralpathstoachievethesamelinkloadbalancing;(2)Ipassbetweenthenetworkswithminimaloverhead;(3)networkstatechangesfastconvergence;(4)summaryroutinginformation.Inordertocontrolthebroadcastdata,therouteroffersmanyvalue-addedfeaturestoenhancetheparknetworkmanageabilityandscalability,therouterIOSsoftwarefeaturesontheTCP/IP,AppleTalk,DECnet,NovellIPX,IBMSNA.DLSw,APPNandotheragreementsspecialsupport.Inthecampusnetwork,fromoneendtotheothersideofroutinghopsiscalledthenetworkdiameter,thediametertotheparkrequiresthedefinitionofwebdesignexperience,whichusethehierarchicaldesignmodel,showninFigure1isarouterHUBstructureofatypicaldesign.Fromonebuildingtoanotherbuildingendhostsro