Introduction
DevelopmentStatus
GigabitEthernetisatechnologybasedonbasicEthernetstandards.GigabitEthernetandthewidelyusedEthernetarefullycompatiblewithFastEthernet,anduseallthetechnicalspecificationsstipulatedbytheoriginalEthernetstandard,includingCSMA/CDprotocol,Ethernetframe,fullduplex,flowcontrolandIEEE802.3Managementobjectsdefinedinthestandard.AsanintegralpartofEthernet,GigabitEthernetalsosupportstrafficmanagementtechnology,whichguaranteesthequalityofserviceonEthernet.ThesetechnologiesincludeIEEE802.1Player2priority,layer3priorityQoScodingbits,specialServiceandResourceReservationProtocol(RSVP).
GigabitEthernetalsoutilizesIEEE802.1QVLANsupport,fourth-levelfiltering,andGigabitthird-levelswitching.GigabitEthernetwasoriginallydesignedasaswitchingtechnology,usingopticalfiberastheuplinkforconnectionsbetweenbuildings.Later,intheconnectionofserversandbackbonenetworks,GigabitEthernethasbeenwidelyused.DuetotheintroductionoftheIEEE802.3abstandard(GigabitEthernetstandardusingcategory5andaboveunshieldedtwistedpair),GigabitEthernetcanbeused.Applicabletoanylarge,mediumandsmallenterprisesandinstitutions.
GigabitEthernethasdevelopedintoamainstreamnetworktechnology.Largeenterprisesaslargeastensofthousandsofpeople,smallandmedium-sizedenterprisesassmallasdozensofpeople,willuseGigabitEthernettechnologyasthepreferredhigh-speednetworktechnologywhenbuildingcorporateLANs.GigabitEthernettechnologyisevenreplacingATMtechnology,becomingthemainforceintheconstructionofmetropolitanareanetworks.
Features
1.GigabitEthernetprovidesaperfectmigrationpath,fullyprotectingtheinvestmentintheexistingnetworkinfrastructure.GigabitEthernetwillretainIEEE802.3andEthernetframeformatsand802.3managedobjectspecifications,sothatenterprisescanupgradetogigabitperformancewhileretainingexistingcables,operatingsystems,protocols,anddesktopapplicationsProgramandnetworkmanagementstrategiesandtools;
2.ComparedwiththeoriginalbackbonenetworksolutionssuchasFastEthernet,FDDI,andATM,GigabitEthernetprovidesanoptimalpath.Atleastfornow,itisareliableandeconomicalwaytoimprovethebackboneconnectionbetweentheswitchandtheswitchandtheconnectionbetweentheswitchandtheserver.Networkdesignerscanbuildahigh-speedinfrastructurethateffectivelyuseshigh-speed,mission-criticalapplicationsandfilebackups.NetworkmanagerswillprovideuserswithfasteraccesstotheInternet,Intranet,MetropolitanAreaNetworkandWideAreaNetwork.
3.TheIEEE802.3workinggroupestablishedthe802.3zand802.3abGigabitEthernetworkinggroups,whosetaskistodevelopGigabitEthernetstandardsthatmeetdifferentneeds.Thisstandardsupportsfull-duplexandhalf-duplex1000Mbps,andthecorrespondingoperationadoptsIEEE802.3EthernetframeformatandCSMA/CDmediaaccesscontrolmethod.GigabitEthernetisalsobackwardcompatiblewith10BaseTand100BaseT.Inaddition,theIEEEstandardwillsupportmultimodefiberswithamaximumdistanceof550meters,single-modefiberswithamaximumdistanceof70kilometers,andcoppercableswithamaximumdistanceof100meters.GigabitEthernetfillsinthedeficienciesofthe802.3Ethernet/FastEthernetstandard.
Construction
TheGigabitEthernetnetworkiscomposedofGigabitswitches,Gigabitnetworkcards,andintegratedwiringsystems.Thegigabitswitchformsthebackboneofthenetwork.Thegigabitnetworkcardisinsertedintotheserverandconnectedtotheswitchthroughawiringsystem.Therecanalsobemany100Mswitchesunderthegigabitswitch,andthe100Mswitchisconnectedtotheworkstation.Thisistheso-called"100MTothedesktop".Insomeprofessionalgraphicsproductionandvideo-on-demandapplications,"GigabittoDesktop"mayalsobeused,andaGigabitswitchisusedtoconnecttoaworkstationwithaGigabitnetworkcard,whichmeetsthedemandforhighbandwidthunderspecialapplications.
Beforebuildinganetwork,whethertouseGigabitor100M,wemuststartfromtheactualsituation,startfromtheapplication,andconsiderwhatfunctionsthenetworkshouldhave.Differentapplicationshavedifferentrequirements,andthereisalmostnonetworkwithasingleservice.However,amongthevariousbusinesses,theproductivebusinessisdefinitelythehighestpriority.Ifvoiceistransmittedoverthenetwork,thenvoiceservicesalsoneedtobeprioritized.Ifthedemandforbusinesspriorityishigh,thenetworkmusthaveQoSguarantees.Suchanetworkmustbeintelligent.Theswitchportcanidentifywhattypesofservicesarepassing,andthenqueueupdifferentservices,andallocatedifferentbandwidthsfordifferentservices,soastoensuretheoperationofkeyservices.Thedataserviceitselfisintelligent,anditcanbetransmittednomatterhowmuchbandwidthitis,justthelengthoftime,butthevoiceorvideoisnotthesame.Ifthebandwidthissmall,itwillbedifficulttohearimmediately,ortheimagewillbejittery.notallowed.SoQoSisveryimportant.Forapuredatanetwork,thedemandforQoSisverylow.Whenplanningthenetwork,youmustfirstunderstandwhichfunctionsarenecessaryandwhichcannotbeconsidered.Forexample,multicastingisoneofthemoreimportantfeatures.Ifimagesneedtobetransmittedonthenetwork,andthenetworkdoesnothavethecharacteristicsofmulticasting,thebandwidthwasteofthenetworkwillbeveryserious,orevenimpossibletoachieve.
Международен стандарт
През януари 1997 г. беше приет първият проект на IEEE802.3z;
През юни 1997 г. проектът V3.1 беше приет. Окончателните технически подробности са формулирани тук;
През юни 1998 г. стандартът IEEE802.3z беше официално одобрен;
През юни 1999 г. абстандартът IEEE802.3 (т.е. 1000Base-T) беше официално одобрен, можете да използвате кабели с усукана двойка за Gigabit Ethernet.
TheGigabitEthernetstandardmainlytargetsthreetypesoftransmissionmedia:single-modefiber;long-wavelaseronmulti-modefiber(called1000BaseLX),short-wavelaseronmulti-modefiber(called1000BaseSX));1000BaseCXmedium,whichcanbetransmittedonabalancedshielded150ohmcoppercable.The1000BaseTstandardsimulatedbytheIEEE802.3zcommitteeallowsthetransmissiondistanceofGigabitEthernetonCategory5,Super5,andCategory6UTPtwisted-pairlinestobeextendedto100meters,sothatmostofthewiringinthebuildingadoptsCategory5UTPtwistedpaircableguaranteestheuser'spreviousinvestmentinEthernetandFastEthernet.Fornetworkadministrators,thereisnoneedtoacceptnewtraining.WiththeknowledgeofEthernetnetworks,theycanmanageandmaintainGigabitEthernet.
ThestandardizationofGigabitEthernetincludesthreemainmodules:encoding/decoding,transceiver,andnetworkmedia.Differenttransceiverscorrespondtodifferentnetworkmediatypes.When1000BASE-LXisbasedonthe1300nmsingle-modeopticalcablestandard,ituses8B/10Bencodinganddecoding,andthemaximumtransmissiondistanceis5000meters.1000BASE-SXisbasedon780nmFibreChanneloptics,using8B/10Bencodinganddecodingmethods,using50micronor62.5micronmultimodeopticalcables,andthemaximumtransmissiondistanceis300metersto500meters.TheSCtypeopticalfiberconnectorusedtoconnecttheopticalfiberisofthesamemodelastheconnectorusedinFastEthernet100BASEFX.1000BASE-CXisastandardbasedoncoppercables,using8B/10Bencodinganddecodingmethods,withamaximumtransmissiondistanceof25meters.1000BASE-Tisbasedonunshieldedtwistedpairtransmissionmedium,using1000BASE-TcopperphysicallayerCopperPHYencodinganddecodingmethod,thetransmissiondistanceis100meters.1000BASE-Tusesall4twistedpairsintransmissionandworksinfullduplexmode.ThisdesignusesPAM-5(5-levelpulseamplificationmodulation)encodingtotransmit250Mbpsoneachpair.Two-waytransmissionrequiresthatallfourwire-pairtransceiverportsmustuseahybridmagneticfieldcircuit.Becauseaperfecthybridmagneticfieldcircuitcannotbeprovided,itisimpossibletocompletelyisolatethetransmittingandreceivingcircuits.Anysendingandreceivinglineswillechotheequipment.Therefore,toachievetherequirederrorrate(BER),theechomustbecanceled.1000BASE-Tcannotfilterthefrequencybandsabove125MHz,buttheuseofscramblingtechnologyandtrelliscodingcanfilterthefrequencybandsafter80MHz.InordertosolvethelimitationofCategory5linesduetonear-endcrosstalkinsuchahighfrequencyrange,appropriatesolutionsshouldbeadoptedtooffsetthecrosstalk.
TheoriginalGigabitEthernetusedhigh-speed780nmfiberchannelopticalcomponentstotransmitsignalsonopticalfibers,andused8B/10Bencodinganddecodingmethodstoachieveserializationandrestorationofopticalsignals.ThedataoperatingrateofFibreChanneltechnologyis1.063Gbps,whichwillbeincreasedto1.250Gbpsinthefuture,enablingthedataratetoreachacomplete1000Mbps.Forlongerconnectiondistances,1300nmopticalcomponentswillbeused.Inordertoadapttothedevelopmentofsilicontechnologyanddigitalsignalprocessingtechnology,amedium-independentlogicalinterfaceshouldbeestablishedbetweentheMAClayerandthePHYlayer,sothatGigabitEthernetcanworkinanunshieldedtwistedpaircablesystem.Thislogicalinterfacewillbeapplicabletotheencodingmethodofunshieldedtwistedpaircablesystemsandisindependentoftheencodingmethodoffiberchannel.ThefollowingfigureillustratesthecompositionofGigabitEthernet.
GigabitEthernet
Therearenotmanyconditionsforupgrading10Mand100MnetworkstoGigabit.Themostimportantthingistheintegratedwiringconditions.GigabitEthernetreferstothebandwidthofthenetworkbackbone,andthebackbonecablingsystemmustmeettherequirementsofGigabitEthernet.Iftheoriginalnetworkcoversmultiplebuildingsseparatedbyseveralhundredmeterstoseveralkilometers,theoriginalbackbonewiringgenerallyusesmulti-modeorsingle-modefiber,whichcanmeettherequirementsofagigabitbackbone,andthereisnoneedtore-laythefiber.Whenthedistancebetweenbuildingsislessthan550meters,generallylayingrelativelyinexpensivemulti-modeopticalfibercanmeettheneedsofGigabitEthernet.
Iftheoriginalnetworkonlycoversonebuilding,andthedistancebetweenthefurthestnetworknodeandthenetworkcenterisnomorethan100meters,theoriginalCategory5orCategory5cablingsystemcanbeused.IftheoriginalwiringsystemdoesnotmeettheCategory5standard,orifabus-typewiringsystemisusedinsteadofastar-typewiringsystem,thenCategory5linesmustbere-routed.
ToupgradetoGigabitEthernet,youmustfirstupgradethenetworkbackboneswitchtoGigabittoincreasethedatatrafficthatthenetworkbackbonecanwithstand,soastoachievethepurposeofacceleratingthenetworkspeed.Theprevious100Mswitcheswereusedasbranchswitches,andtheprevioushubscanbeusedwherethereareinsufficientwiringpoints.TherearemanyGigabitswitchproducts,whichcanbeselectedaccordingtoactualconditionssuchasnetworkrequirementsandbudgets.
Theserveronthenetworkneedstohandlealotofdata.Ifthenetworkbackboneisupgradedtogigabit,buttheservernetworkcardisstillatthelevelof100M,theservernetworkcardwillbecomethebottleneckofthenetwork,andgigabitmustbeusedThenetworkcardcaneliminatethisbottleneck.Thesolutionistoaddagigabitnetworkcardtotheoriginalserver.Notethat64-bitPCIGigabitnetworkcardsshouldbeselectedfirst,anditsperformanceishigherthanordinaryPCIGigabitnetworkcards.Gigabitnetworkcardcanbeselectedaccordingtoactualconditionssuchasnetworkrequirementsandbudget.
Thebackboneofthenetworkhasbeenupgraded,andthebranchesofthenetworkshouldbeupgradedaccordingly.Iftheoriginalusercomputerhasalreadyinstalleda10M/100Madaptivenetworkcard,youdon’tneedtoupgradethenetworkcard,justconnectthenetworkcardtoa100Mswitch;iftheoriginal10Mbpsnetworkcardisused,youneedtochangethenetworkcardto10M/100Madaptivenetworkcard,soastoincreasethespeedofworkstationsaccessingtheserver.
Prospectforecast
Itisestimatedthatbefore2005,thedatatransmissionvolumewillincreaseby3timeseachyear,andwillexceedthevoicetransmissionvolumethatyear,becomingthemaintransmissionmethodofglobalcommunicationnetwork.Inthefaceofever-increasingdatastreamsandmultimediaservices,themarketscaleofhigh-endnetworkproductswithlarge-capacity,high-speed,andmulti-functionmoduleswillcontinuetoexpand.ItisforeseeablethatthemarketshareofGigabitEthernetswitcheswillbecomelargerandlarger.WiththedevelopmentoftheInternetandtheemergenceofendlessapplicationsonthenetwork,10GigabitEthernetwillbethemainstreaminthefuture,andGigabitEthernetwillstillbethemainstreaminthemarket.
Technicaladvantages
Inordertomaintainthemaximumcollisionareawithadiameterof200metersandtheminimumCSMA/CDcarriertimeinthelocalareanetwork,theEthernettimeslicehasbeenextendedfrom512bitsto512bytes(4096bits),theminimumframelengthbecomes512bytes,andthemaximumframelengthisstill1518bytes.ThecarrierextensionfeaturesolvestheinherenttimingproblemofCSMA/CDwithoutmodifyingtheminimumpacketsize.Althoughthesechangesmayaffecttheperformanceofsmallinformationpackets,thiseffecthasbeenoffsetbyacharacteristiccalledpacketbursttransferintheCSM/CDalgorithm.ThebiggestadvantageofGigabitEthernetisitscompatibilitywithexistingEthernet.
Like100M-bitEthernet,GigabitEthernetusesthesameframeformatandframesizeas10M-bitEthernet,andthesameCSMA/CDprotocol.ThismeansthatthemajorityofEthernetuserscanupgradetheexistingEthernetsmoothlyandwithoutinterruptionwithoutaddingadditionalprotocolstacksormiddleware.Atthesametime,GigabitEthernetalsoinheritsotheradvantagesofEthernet,suchashighreliabilityandeasymanagement.
Comparedwithothertechnologies,GigabitEthernethastheadvantageoflargebandwidthandstillhasroomfordevelopment.Therelevantstandardsorganizationsareformulatingtechnicalspecificationsandstandardsfor10GEthernet.Atthesametime,prioritycontrolmechanismsandprotocolstandardsbasedontheEthernetframelayerandIPlayer,aswellasvariousQoSsupporttechnologieshavegraduallymatured,providingafoundationfortheimplementationofapplicationsrequiringbetterservicequality.Withtheadvancementofopticalfibermanufacturingandtransmissiontechnology,thetransmissiondistanceofGigabitEthernetcanreachupto100kilometers,whichmakesitgraduallybecomeatechnologychoiceforbuildingmetropolitanareanetworksandevenwideareanetworks.
TheadvantageofusingGigabitEthernetinthebackboneisthatGigabitEthernetwillprovide10timestheperformanceofFastEthernetandiscompatiblewiththeexisting10/100Ethernetstandard.Atthesametime,thevirtualnetworkstandard802.1Qandprioritystandard802.1pdevelopedfor10/100/1000Mbpshavebeenpromoted,andthegigabitnetworkhasbecomethemainstreamtechnologythatformsthebackboneofthenetwork.
ThefirstGigabitEthernetstandard802.3,whichwasformulatedinJune1998,targetsfull-duplexlinksusingopticalfibercablesandshort-distancecoppercables.Thestandard802.3abforhalf-duplexandremotecopperwirecableswasintroducedin1999.
Thehigh-speedmulti-layerdatapacketforwardingcapabilityofGigabitEthernetisapowerfulexamplethatGigabitEthernettechnologycanprovidethebestperformance-to-priceratio.Notonlythat,GigabitEthernettechnologyisalsoverybeneficialforreducingthelong-termcostofownershipofthenetwork.
Switchingtechnology
Sincetheendof1996,somecompanieshavesuccessivelyintroducedswitchproductsthatintegratelayer2switchingandlayer3routing.Thistechnologyiscalled"multi-layerswitching(multilayerswitching)".Itaddsroutinglayerservicestolayer2switchingtechnology,supportsselectivebroadcastandmulticastsuppression,supportspacketforwardingandfirewallfunctionsbetweenVLANsandVLANs,andfullysupportsTCP/IPandIPXrouting.
Afternearly4yearsofdevelopment,thesefunctionshavebeencontinuouslyimprovedandstrengthened,makingtheperformance-priceratioofmulti-layerswitches8to16timeshigherthantraditionalrouters.Thenewgenerationofmulti-layerswitcheswithGigabitEthernetswitchingtechnologyasthecore,canprovidemoreattractiveperformance-priceratio,andisthemostidealswitchthatcanprovidemulti-layerswitchingindepartmentalnetworksanddatacenternetworkstoreplacetraditionalrouters.Atthesametime,itsdirecttransmissiondistancehasnowreached130kilometers,whichcanfullyrealizealargeenterpriseLANwithGigabitEthernetasthebackbone,andthebackbonetransmissionrateis2Gbps(fullduplexmode).
ThemainfactorthatpromotesthedevelopmentoftechnologyThebiggestfactorthatpromotesthedevelopmentofhigh-speedmulti-layerswitchingtechnologyisthemassdeploymentoftheInternetandIntranetusingcheap10/100Madaptivenetworkcards.Thenetworkhasbecomefartherandfartherawayfromthetraditionalc/scomputingmodel'shierarchicalstructure,andthetraditional80/20trafficruleofthec/smodelhasbecomeathingofthepast.Intermsofnetworkdesign,thetraditionalrouterplusHuborLayer2switchnetworkdeploymentmodelwillalsobecomehistory.
Освен това, интранет поддържа разнообразие от по-сложни и чувствителни към честотната лента мултимедийни потоци от данни, като данни, файлове, картини, анимация, звук и видео. Потребител в интранет изисква поне 50% до 100% повече честотна лента от потребител, който не е в интранет. В същото време широколентовият достъп се превърна в разработка nd
AnotherissueworthnotingisthatprovidinguserswithafastEthernetconnectioncanprovidemorebandwidthmargintohandlesuddentraffic,whichisunmatchedby10BASE-Ttechnology.BursttrafficisoneofthecharacteristicsofIPnetworkapplications.LowcostandhighbandwidthmakeFastEthernetwidelyusedonboththeusersideandtheserverside.
Inordertostrikeabalancebetweennon-blockingandtheabilitytohandlesuddentrafficflows,thenewgenerationofswitchplatformsmustprovidebackboneconnectionsthatare8-16timesfasterthantheuser’srequestconnection.ThenetworkbackbonejustsatisfiestheservicerequestofthefastEthernetconnectionontheuserside.Thisisveryimportanttoadequatelyhandlebursttraffic.
Atthesametime,incampusnetworksormetropolitanareanetworks,nomatterhowmanynetworklayersarespanned,randomintranettrafficisrequiredtoprovideend-to-endconsistenthighperformance.Inordertoachievethis,itistheonlysolutiontohavebothhigh-performancelayer2andlayer3forwardingcapabilitiesinaswitch.
Thenon-blockingcapabilityandselectiveforwardingfunctionarethemainrequirementsofusers.Variousveryeffectivenetworkmanagementtoolsenablenetworkadministratorstoeffectivelyandefficientlyinjectbusinessstrategiesintotheforwardingengine,anditsperformancecanbemonitoredinrealtimethroughnetworkmanagementsoftware.Thiswillfundamentallyhelpusersdetermineanddelivertherequirednetworkservicesaccordingtothecompany'sshort-termandlong-termbusinessdevelopmentneeds.ThenewgenerationofGigabitEthernetswitchessupportthesefeaturesandservices,aswellascommonroutingprotocolssuchasIP/RIPorIP/OSPF.Thisalsogreatlyreducesthecomplexityofnetworkequipment.
Objectiveprinciples
Thehighperformanceofthenetworksystemrequiresthecoreswitchtomeettherequirementsofthemassivedataexchangeofthenetworkcenter,andthecommunicationlinkbandwidthoftheuplinkcentercanmeettheperformancerequirementsoftheapplicationonthenetwork.Regardlessofwhetheritisanenterprisenetwork,ametropolitanareanetwork,orawideareanetwork,theinformationapplicationsonitaredevelopingatanunprecedentedspeed,andnewmultimediaapplicationsandnewdataapplicationsplacehigherrequirementsonbandwidth.Inthecaseofenterprisesgenerallyadoptingtheintranetnetworkmodel,itsWWWserver,FTPserver,LotusNotesgroupwareapplicationserver,NovellServerandotherserverclusterssupporttheentireenterprise'sinformationserviceenvironment.Theclientapplicationsoftwareofusersinvariousdepartmentsoftheenterpriseaccessesthecentralserverthroughthenetwork,requestsapplications,andqueriesthedatabase.Theloadflowofthenetworkismainlythedataexchangefromtheedgedevicetothecore.Withthedevelopmentofenterprisebusiness,theexpansionofthenetworkscale,andtheincreaseintheamountofinformationexchangeoftheapplication,theenterprisenetworkusuallyfirstoccursinthecoreofthecommunicationbottleneckphenomenon.ToimprovethenetworkdataexchangeperformanceoftheenterprisecampusLAN,thefirststepistoexpandtheexchangeperformanceofthecoreswitchandincreasethedatacommunicationbandwidthfromtheedgedevicetothecoretoreducethebottleneckoftheentirenetworkandimprovetheperformanceandefficiencyofapplicationsoftware.Therefore,intheprincipleofdesigninganenterprisecampusLAN,weshouldfirstconsiderthedataexchangeprocessingcapabilitiesofthecoreequipmentrequiredbythenetworkscale,andthelinkbandwidthfromtheedgeequipmenttothecore.
Reliabilityandavailability
Thehighreliabilityofequipmentandhighavailabilityofthesysteminthenetworksystemdesign;allkeycomponentsofthecoreswitcharerequiredtoachieveredundancyandcanbereplacedonline(plug),therecoverytimeofthefaultiscompletedwithinasecondinterval.Themulti-levelfault-tolerantdesignfurtherimprovestheavailabilityofthesystembasedonthehighreliabilityofasingledevice.
Asfarasenterpriseapplicationsareconcerned,itusesadvancedcomputer,networkandotherinformationtechnologiestorealizeautomaticcontroloftheproductionprocessandpaperlessofficeautomation,whichimprovestheefficiencyandlevelofproductionandmanagementoftheenterprise.Theinfrastructuresupportingenterpriseapplicationsistheenterprise'scampusnetwork.Itsworkingconditionswilldirectlyaffecttheenterprise'sofficeapplicationenvironment,businessenvironmentsuchastransaction,production,development,design,financialmanagement,partsmanagementandotherenvironments,informationretrieval,databasequery,Internetbrowsingandothernecessaryservicefacilitiestosupportthenormaloperationoftheenterprise.Thereliabilityrequirementofthenetworkistheprimaryconditiontoensurethenormaloperationoftheenterpriseapplicationenvironment.Whilethenetworkrequiresreliability,italsorequiresthenetworktohavehighavailability.Thechoiceofnetworkequipment,especiallythecorechassis-typeequipment,shouldbeabletoconfigureredundantcomponents.Thereisnosinglepointoffailureforkeycomponents.Thatistosay,componentssuchasswitchpowersupplies,fans,switchingengines,andmanagementmodulescanberedundantlybackedup.Thedamageofanypartofoneofthemwillnotaffectthenormaloperationoftheequipmentandwillnotaffectthenetworkconnection.Anotherrequirementforthereliabilityandfaulttoleranceofthenetworkequipmentisthatwhenthedamagedpartsoftheequipmentarereplaced,thereisnoneedtoshutdown,andthereisnoneedtorestartafterreplacingtheparts.Thatistosay,thereplacementofthepartscanbeoperatedonline,whichcanreducethedowntime.Tothesmallest.Ontheprincipleofdesigningenterprisecampusnetworks,itisveryimportanttoimprovetheprinciplesofhighreliabilityandhighavailabilityofthenetwork.Notonlytheequipmentcomponentsarerequiredtoberedundant,butalsothenetworklinkredundancyisrequired,whichcancombinethephysicallayer,linklayerandThethirdlayeroftechnologyisimplementedtoensurethatthenetworkcanprovideinformationaccessservicesatanytimeandanyplace.
Scalability
Thescalabilityrequirementsofnetworkdesignincludethescalabilityofswitchhardwareandtheabilityofthenetworktoimplementnewapplications.Flexiblescalabilityrequirementsforcoreswitches:Thecoreswitchesshouldhaveflexibleportexpansioncapabilitiesandmoduleexpansioncapabilitiestomeettheexpansionofnetworkscale;atthesametime,improveperformancetomeethigherperformancerequirements.Abilitytosupportnewapplications:Theproducthasthetechnicalpreparationtosupportnewapplications,andcanimplementnewapplicationsquicklyandeasily.
Scaleandusers
Whendesigninganetworkplan,thefirstthingtodoistomeettheneedsofnetworkusersoftheexistingscale.Atthesametime,consideringfuturebusinessdevelopmentandscaleexpansion,thenetworkshouldbedesignedIthasflexibleexpansioncapabilitiesforuserports.Thecoreequipmentisthehuboftheentirenetwork.Theexpansionofthenumberofuserportsrequirestheadditionofequipmentintheedgeworkinggroupofthewiringcloset.Whentheedgeequipmentisadded,thenumberofportsconnectedtothecorebackboneequipmentisrequiredtoincreaseaccordingly.Therefore,thecoreequipmentshouldbeabletoincreasethenumberofmodules.Toflexiblyincreasethenumberofports.Thechassisdesignofthecoreequipmentshouldhaveastrongbackplanebandwidthandenoughloadslotcapacity.Fortheswitch,thecoreswitchingengineshouldbeabletoperformportdatapacketswitchingwithoutblockingunderthemaximumconfiguration,andtheexpansionofthemoduledoesnotaffecttheswitchingperformance.Theuseofadistributedswitchingstructureisthebestsolutiontorealizethisprinciple.Thedistributedswitchstructurerealizestheparalleldataexchangeprocessingoftheswitchesandoptimizestheperformanceofthenetwork.Thedistributedstructurecombininglocalandglobalswitchingreducesthecoreswitchingengine.pressure.Therefore,intheprincipleofdesigninglarge-scalecampusnetworks,distributedswitchesaregenerallyusedtoachieveflexiblemoduleandportexpansioncapabilities.
Security
Networksecurityisveryimportanttonetworkdesign.Reasonablenetworksecuritycontrolcaneffectivelyprotectandcontroltheinformationresourcesintheapplicationenvironment.Networkaccess,flexibleimplementationofnetworksecuritycontrolstrategies.Intheenterprisecampusnetwork,onlysystemadministratorshavethepowertooperateandcontrolkeyapplicationserversandcorenetworkequipment.Theapplicationclientonlyhastherighttoaccesssharedresources,andthenetworkshouldbeabletopreventanyillegaloperations.Itshouldbepossibletoperformpacketfilteringcontrolfunctionsbasedonprotocol,Macaddress,andIPaddressonthecampusnetworkequipment.Inthedesignoflarge-scalecampusnetworks,dividingvirtualsubnetscaneffectivelyisolatealargenumberofbroadcastsinthesubnetsontheonehand,andontheotherhandisolatethecommunicationbetweennetworksubnets,controlresourceaccessrightsandimprovenetworksecuritysex.Inthedesignofthecampusnetwork,thesecuritycontrolcapabilityofthenetworkmustbeemphasized,sothatthenetworkcanbeconnectedarbitrarily,andtheaccesstothenetworkcanbecontrolledfromthesecondandthirdlayers.
Manageability
Networkmanageabilityrequirements:anydeviceinthenetworkcanbecontrolledthroughthenetworkmanagementplatform,andnetworkequipmentstatus,faultalarms,etc.canallbemanagedthroughthenetworkmanagementTheplatformperformsmonitoring,simplifiesmanagementthroughthenetworkmanagementplatform,andimprovestheefficiencyofnetworkmanagement.
Innetworkdesign,itisessentialtochooseadvancednetworkmanagementsoftware.Networkmanagementsoftwareisusedinnetworkequipmentconfiguration,networktopologydisplay,networkequipmentstatusdisplay,networkequipmentfailureeventalarm,networktrafficstatisticsanalysisandbilling,etc.Theapplicationofnetworkmanagementsoftwarecanimprovetheefficiencyofnetworkmanagementandreducetheburdenonnetworkmanagementpersonnel.Thegoalofnetworkmanagementistoachievezeromanagement,astrategy-basedmanagementmethod,andnetworkmanagementisgloballycontrolledbythemanagementstrategyserverbyformulatingaunifiedstrategy.Theweb-basednetworkmanagementinterfaceisthedevelopmenttrendofnetworkmanagementsoftware,andtheflexibleoperationmodesimplifiestheworkofmanagementpersonnel.Inthedesignofthecampusnetworkequipmentselection,thenetworkequipmentisrequiredtosupportthestandardnetworkmanagementprotocolSNMP,whilesupportingtheRMON/RMONIIprotocol,andthecoreequipmentisrequiredtosupporttheRAP(remoteanalysisport)protocoltoimplementsufficientnetworkmanagementfunctions.Inprinciple,thedesignofthecampusnetworkshouldrequirethemanageabilityofequipment,whileadvancednetworkmanagementsoftwarecansupportnetworkmaintenance,monitoring,configurationandotherfunctions.
Standardizationoftheprotocol
Networkequipmentadoptsopentechnologyandsupportsstandardprotocols:standardprotocolsareusedtoprotectusers’investmentandimproveequipmentinteroperability.Theequipmentusedinnetworkdesignrequiresmainstreamtechnologyanddevelopedstandardprotocols,hasgoodinteroperability,andcansupportdifferentseriesofproductsofthesamemanufacturer,andseamlessinterconnectionandcommunicationbetweenproductsofdifferentmanufacturers.Ontheprincipleofdesigningthecampusnetwork,thespecialadvancedtechnologyofdifferentmanufacturers'productsmustbeused,andthestandardizationofequipmenttechnologyandprotocolmustbeemphasizedtoreduceequipmentinterconnectionproblemsandnetworkmaintenancecosts,sothatuserinvestmentcanbeeffectivelyprotected.
Itshouldbeconsideredwhethertheselectedequipmentisupgradeable.Afterthenewstandardappears,thesystemshouldbeabletoupgradetothenewstandard.Therefore,focusonthestatusofproductmanufacturersinthecorrespondingproductandtechnicalfieldsandtheirabilitytoparticipateinstandardization.
Intoday'sworld,thedevelopmentofcommunicationtechnologyandcomputertechnologyischangingwitheachpassingday.Networkdesignmustnotonlyadapttothetrendofnewtechnologydevelopment,ensuretheadvancednatureofthesystem,butalsotakeintoaccountthetechnicalmaturity,andreducetheriskscausedbyimmaturefactorsinnewtechnologiesandnewproducts.
Решение
Най-голямото предимство на Gigabit Ethernet е неговата съвместимост със съществуващия Ethernet. Подобно на 100M-bitEthernet, GigabitEthernet използва същия формат на рамка и размер на рамката като 10M-bitEthernet и същия CSMA/CDпротокол.
Asafeatureofcampusnetworkapplications,mostapplicationsarenotsensitivetodelayandbandwidth,andcanautomaticallyidentifydelaychangesthroughtheTCP/IP"slowstart"mechanism,anddynamicallyadapttothebandwidthprovidedbyTCP,Someapplicationsrequirereal-timeservicetransmissionsupportandQoSserviceguarantee.Thispartoftheapplicationaccountsforasmallproportion.Withtheaccelerationofthemodernizationofteachingmethods,thegradualpopularizationofmultimediacoursewareproductiontools,andthegradualenrichmentofmultimediacourseware,theproportionisexpectedtograduallyincrease.Themainbottleneckofreal-timeservicetransmissionoverIPnetworkisthatroutersusesoftwaretorealizerouteidentification,calculationandpacketforwarding.Duetotheslowspeedofrouteidentificationanddataforwarding,thedelayanddelayjitterarelarge,thequalityofservice(QoS)cannotbeguaranteed.Sincethesecondhalfof1997,somecompanieshavesuccessivelyintroducednewwire-speedroutingswitchesthatusehardwarededicatedcircuits(ASIC)forroutingidentification,calculation,andforwarding.Thestructureofthiswire-speedroutingswitchissimilartothatoftheL2switch.IthasboththeL3routerpacketforwardingfunctionandtheL2switchingfunction.SomemanufacturersalsoaddsomeL4applicationlayerfunctions.
ToprovideQoSonthepacket-switchedIPnetwork,theservicemustbeclassified,andtheclassificationservice(CoS)mustbeimplemented.Equipmentmanufacturersgenerallyusecongestionmanagementtoensurenetworkperformanceandprovidetherequiredbandwidthforsomespecializedservices.OneapproachistouseRED(RandomEarlyLoss)todetectandintelligentlyidentifytheinstantaneoussurgeintraffictodistinguishitfromrealnetworkcongestiontoavoidnetworkcongestion.Byidentifyingtheservicecategory(802.1P)fromtheIPv4serviceclassificationidentifier(TOS)intheIPpacketheader,thepriorityofthedataflowisdetermined,andacertainqueuepriorityalgorithmisusedtoensuretheQoScapability.Youcanalsouseanaccesscontrollist(ACL)todefinepoliciesanddeterminethepriorityofdatastreams.Withtheadvancementoftechnology,itisforeseeablethatQoScapabilitiesonhigh-speedIPnetworkswillreachasimilarlevelofFR/ATMnetworks.
Onthebasisofanalyzingandcomparingtheperformance,price,andserviceofavarietyofL2/L3/L4wire-speedroutingswitchesinthemarket,atotalof11CajunP550RroutingswitchesfromLucent(Lucent)wereselectedasthecampusNetworkbackboneswitch.Itsmaintechnologyandperformanceindicatorsare:
Капацитет на задната платка45,76 Gbps
Капацитет на превключване 22,88 Gbps
Капацитет на превключване на слой 233 000 000pps
Капацитет на превключване на слой 318 000 000pps
Множество L2/L3 интерфейсни модули
Резервни вентилатори, захранвания
Взаимна съвместимост на OpenTrunk/VLAN
Поддръжка на CoS/QoS/RSVP
Innetworkdesign,backboneswitchesareinterconnectedwitheachotherthroughGigabitEthernet.AllswitchesareequippedwithL3switchingenginetoimplementdistributedroutingstrategies,therebyreducingthepressureonL3routinganalysisandpacketforwardingofthecentralswitchandcontrollingthescopeofthebroadcastdomain.Thenetworkdesignandequipmentconfigurationcarefullyconsiderthephysicalandlogicalredundancyofequipment,linesandrouting,thefirewallsettingsandsecuritypoliciesofthenetworkcenterservergroup.
Технология
1000Base-T технология
С пускането на Националната техническа спецификация за Gigabit Ethernet SwitchEquipment, GigabitEthernetПриложението на технологията е разработено внезапно.
1000Base-T(GigabitEthernetimplementedonCategory5twistedpair)hasbecomeoneofthebestchoicesfornetworkmanagersduetothefollowingreasons.First,itmainlymeetstherapidlyincreasingdemandforbandwidthinexistingnetworks;secondly,inthesenetworks,emergingapplicationscontinuetoappear,andswitchesattheedgeofthenetworkarealsoincreasing.GigabitEthernetcanprotectthecompany'sexistinginvestmentsinEthernetandFastEthernetfacilities;third,itcanprovideasimple,effectiveandinexpensiveperformanceimprovementmethod,whilecontinuingtousealargenumberofexistingHorizontalcabletransmissionmedium.
Принцип на 1000Base-T технология
Transmissionmediaspecification
GigabitEthernetcanusetheexistingcablefacilities,sothatithasagoodperformancepriceCompare.Itcanbeusedonthenetworkinfloors,buildingsandcampusesbecauseitcansupportmultipleconnectionmediaandawiderangeofconnectiondistances.Inparticular,GigabitEthernetcanrunonthefollowingfourmedia:opticalfiber,withamaximumconnectiondistanceofatleast5kilometers;Modularfiber,withamaximumconnectiondistanceofatleast550meters;balanced,shieldedcoppercable,withamaximumconnectiondistanceofatleast25meters;Category5lines,withamaximumconnectiondistanceofatleast100meters.
TheIEEE802.3zGigabitEthernetstandardwasapprovedinJune1998.Itdefinesthreetransceiversforthreetransmissionmedia:1000Base-LX,1000Base-SXand1000Base-CX.Amongthem,1000Base-LXisusedtoinstallsingle-modeopticalfiber,1000Base-SXisusedtoinstallmulti-modeopticalfiber,and1000Base-CXisusedtobalanceandshieldcoppercables.Itcanbeusedforinterconnectionincomputerrooms.1000Base-LXtransceiverscanalsobeusedformultimodeopticalfibers,withatransmissiondistanceofatleast550meters.
GigabitEthernetLayering
Anotherspecialworkinggroup,IEEE802.3abhasdefinedthephysicallayerforrunningGigabitEthernetonthebasisofCategory5lines.TheIEEEStandardizationCommitteeapprovedthe1000Base-TstandardinJune1999.1000Base-Tcancontinuetousetheexistingcablefacilities,anditstipulatesthatthetransmissiondistanceontheCategory5linecanbeupto100meters.
Някои други важни спецификации на 1000Base-T правят технология с ниска цена, трудна за разбиване и с добра производителност. На първо място, тя поддържа EthernetMAC и е обратно съвместима с 10/100Mbps Ethernet технология; второ, много продукти на 1000Base-T ще поддържат 100/1000автоматично договаряне функция, така че 1000Base-T може да бъде прекаран директно през бързата реализация на надстройка на мрежата Ethernet; трето, 1000Base-T е технология с висока производителност, която предава 10 милиарда бита, от които няма да има повече от един нов грешен бит на данни (коефициентът на битова грешка е по-малък от 10-10, което е същото като процентът на битова грешка на 100Base-T е сравним).
Спецификация на кабела
1000Base-T посочва, че данните могат да се предават по балансирани усукани двойки кабели от категория 5. ANSI/EIA/TIA-568-A(1995) определя производителността на използваните усукани двойки от четири чифта и пет категории. EXT) са посочени в TIA/EIA-TSB-95. Стандартът за кабели от категория 5 е определен в ISO/IEC11801:1995 ("Информационна технология: Общи кабели за потребителско оборудване от предния край"). Второто условие на ISO/IEC11801:1995 определя някои други параметри за производителност на кабела за поддръжка на Gigabit Ethernet.
Физическа структура
1000Base-Tis, специално проектиран за предаване на данни по усукани двойки кабели от категория 5. Скоростта на предаване от 1Gbps може да се разглежда еквивалентно като четири двойки меки усукани двойки, а скоростта на предаване на всяка двойка е 250Mbps(250Mbps×4=1Gbps).
1000Base-Tand100Base-Tusethesametransmissionclockfrequency(125MHz),butuseamorepowerfulsignaltransmissionandencoding/decodingscheme,whichcanbecomparedto100Base-TonthelinkTtransmitstwiceasmuchdata.Thefollowingisacomparisonofthesetwotechnicalspecifications:
1000Base-T:125MHz×2bit=250Mbps
1000Base-TX:125MHz×2bit-symbol=125Mbit-symbol/s
Моля, обърнете внимание: 125Mbits-символ/sеквивалентно на 100Mbps, тъй като 1000Base-Tusesa4B/5Bencoding-преди подаването на сигнала по кабела за предаване, всеки 4bitsданните се преобразуват в 5-bits-символи;ефективната скорост на трансфер на битове е:125×4/5=100Mbps.
1000Base-Tencoding
За да се използват рентабилно 4 до 5 типа UTP, IEEE802.3 не използва 8B/10 кодиране, но дефинира логика в MAC подслоя и PHYслоя, интерфейсът позволява въвеждането на по-рентабилни схеми за кодиране. Поради ограничението на наличната честотна лента очевидно е, че всяка двойка от Категория 5UTP не трябва да надвишава 125 Mbaud (когато Категория 5UTP е 62,5 MHz, нейният ACR е 30,6 dB). Като се има предвид, че тя може да покрие 28=256 и да минимизира броя на символите в мултиплексната система, пет нива (кунарен) По този начин (1000/4)×(4/8)=125Mbaud може да отговори на ограничението на наличната честотна лента.
Ако се използва кодиране на четири нива (четвъртири), горните изисквания също могат да бъдат изпълнени и то може също да покрива 28=256, но излишно едно от кодирането на пет нива (петици) може да се използва за другите четири нива на код за коригиране на грешки.
Последният 1000Base-Twhitepaper на GigabitEthernet Alliance препоръчва използването на код PAM-5, всеки символ (вземете една от +2,+1,0,-1,-2) съответства на две цифри двоична информация (четири нива представляват два бита, едно ниво се използва за код за корекция на грешка).Кодът за корекция на грешка приема 4- Реализацията на тези зависи главно от технологията на интегрираната схема и технологията за цифрова обработка на сигнали (DSP).
1000Base-TcansupporttheexistingFastEthernetandV.90/56Kmodemtechnologiesthathavebeentestedinpractice,therebyachievingagoodperformance-priceratio.AdvancedDSPsthatimplementsignaltransmissionandencoding/decodingtechniquesin802.3FastEthernetandV.90or56Kmodemscanalsobeusedtoimplement1000Base-T.
Предимства за развитие
GigabitEthernetisanewtypeofhigh-speedlocalareanetwork,whichcanprovide1Gb/scommunicationbandwidth,andadopts10/100MEthernethasthesameCSMA/CDprotocol,frameformatandframelength,soitcanachieveasmoothandcontinuousnetworkupgradeonthebasisoftheoriginallow-speedEthernet,whichcanmaximizetheprotectionoftheuser'spreviousinvestment.
Conclusion
AsmoreandmoredesktopcomputersandworkgroupsupgradetoFastEthernet,thecentralizedbusinessofthebackboneofthenetworkwillincreasesubstantially.Inordertohandlethiskindofbusiness,allnewbackboneswitchesshouldsupportGigabitEthernetuplinks.GigabitEthernetswitchesinthebackbonenetworkcanbeusedtoconnecthightransactionrateserversandnetworksegmentswitchesforcentralizedFastEthernetworkinggroups.IftheopticalfibernetworkconnectionmodeofGigabitEthernetsolvesthehigh-speedconnectionbetweenbuildings,then1000Base-TGigabitEthernettechnologyisusedtosolvethehigh-speedconnectionbetweenfloorsandevenbetweenoffices.
Други типове
Стандартен Ethernet
В началото само Ethernet има пропускателна способност от 10Mbps,и използва многократен достъп на оператори с откриване на сблъсък (CSMA/CD,CarrierSenseMultipleAccess/CollisionDetection)метод за контрол на достъпа, този ранен 10MbpsEthernet се нарича стандартен Ethernet.Ethernet може да използва дебел коаксиален кабел, тънък коаксиален кабел, неекранирана усукана двойка, екранирана усукана двойка и оптично влакно и друга среда за предаване за връзка, а в стандарта IEEE802.3 са формулирани различни медии за предаване .Стандарти за физически слой. В тези стандарти предното число показва скоростта на предаване, единицата е "Mbps", последната цифра показва дължината на единичен сегмент от мрежовия кабел (основната единица е 100 м), Base означава "базова лента", а Broad означава "широколентов".
·10Base-5 използва дебел коаксиален кабел с диаметър 0,4 инча и импеданс 50 Ω, известен също като дебел кабел Ethernet, максималната дължина на мрежовия сегмент това е 500 m, методът на предаване на основната лента, топологията е тип шина; 10Base－Основното хардуерно оборудване на мрежата от 5 групи включва:thickco аксиален кабел, Ethernet карта с AUI гнездо, повторител, трансивър, приемо-предавателен кабел, терминатор и др.
·10Base-2 използва тънък коаксиален кабел с диаметър 0,2 инча и импеданс 50 Ω, известен също като тънък кабел Ethernet. Максималната дължина на мрежовия сегмент е 185 m, методът на предаване на базовата лента и топологията е тип шина; 10Base-2Основното хардуерно оборудване на мрежата включва: тънък коаксиален кабел, E мрежова карта с BNC гнездо, ретранслатор, T-конектор, терминатор и др.
·10Base-Tusest усукана двойка, максималната дължина на мрежовия сегмент е 100m, а топологията е във формата на звезда; основното хардуерно оборудване на 10Base-Tnetwork включва: Категория 3 или Категория 5 неекраниран кабел с усукана двойка, Ethernet карти с RJ-45 гнезда, концентратори, превключватели , щепсели RJ-45 и др.
·1Base-5 използва кабел с усукана двойка, максималната дължина на мрежовия сегмент е 500 m, а скоростта на предаване е 1 Mbps;
·10Broad-36 използва коаксиален кабел (RG-59/UCATV), максималният обхват на мрежата е 3600 m, а максималната дължина на мрежовия сегмент е 1800 m, което е широколентов метод на предаване;
·10Base-Fuses оптична среда за предаване и скоростта на предаване е 10Mbps.
FastEthernet
Withthedevelopmentofthenetwork,thetraditionalstandardEthernettechnologyhasbeenunabletomeettheincreasingdemandfornetworkdatatrafficspeed.BeforeOctober1993,forLANapplicationsrequiringdatatrafficabove10Mbps,onlytheopticalfiberdistributeddatainterface(FDDI)wasavailable,butitwasaveryexpensiveLANbasedon100Mpbsopticalcable.InOctober1993,GrandJunctionlaunchedtheworld'sfirstfastEthernethubFastch10/100andnetworkinterfacecardFastNIC100,andthefastEthernettechnologywasofficiallyapplied.Subsequently,Intel,SynOptics,3COM,BayNetworksandothercompanieshavealsolaunchedtheirownfastEthernetdevices.Atthesametime,theIEEE802engineeringgroupalsoconductedresearchonvariousstandardsof100MbpsEthernet,suchas100BASE-TX,100BASE-T4,MII,repeater,fullduplexandotherstandards.InMarch1995,IEEEannouncedtheIEEE802.3u100BASE-TFastEthernetstandard(FastEthernet),andthusbegantheeraofFastEthernet.
ComparedwiththeoriginalFDDIworkingat100Mbpsbandwidth,FastEthernethasmanyadvantages.ThemostimportantthingisthatFastEthernettechnologycaneffectivelyprotecttheuser’sinvestmentintheimplementationofwiringinfrastructure.ItsupportsTheconnectionofcategory3,4,5twistedpairandopticalfibercaneffectivelyutilizetheexistingfacilities.TheshortcomingsofFastEthernetareactuallytheshortcomingsofEthernettechnology,thatis,FastEthernetisstillbasedonCSMA/CDtechnology.Whenthenetworkloadisheavy,itwillcauseadecreaseinefficiency.Ofcourse,thiscanbecompensatedbyswitchingtechnology.The100MbpsfastEthernetstandardisdividedintothreesub-categories:100BASE-TX,100BASE-FX,and100BASE-T4.
·100BASE-TX:isafastEthernettechnologythatusesCategory5data-levelunshieldedtwistedpairorshieldedtwistedpair.Itusestwopairsoftwistedpairs,onepairforsendingandonepairforreceivingdata.The4B/5Bencodingmethodisusedinthetransmission,andthesignalfrequencyis125MHz.ComplywithEIA586'sCategory5wiringstandardandIBM'sSPTCategory1wiringstandard.UsethesameRJ-45connectoras10BASE-T.Itsmaximumnetworksegmentlengthis100meters.Itsupportsfull-duplexdatatransmission.
·100BASE-FX:ItisakindoffastEthernettechnologythatusesfiberopticcable,whichcanusesingle-modeandmulti-modefiber(62.5and125um).Themaximumdistanceofmultimodefiberconnectionis550meters.Themaximumdistanceofsingle-modefiberconnectionis3000meters.The4B/5Bencodingmethodisusedinthetransmission,andthesignalfrequencyis125MHz.ItusesMIC/FDDIconnector,STconnectororSCconnector.Itsmaximumnetworksegmentlengthis150m,412m,2000morlongerto10kilometers,whichisrelatedtothetypeoffiberusedandworkingmode,anditsupportsfull-duplexdatatransmission.100BASE-FXisparticularlysuitableforapplicationsinenvironmentswithelectricalinterference,large-distanceconnections,orhigh-securityenvironments.
·100BASE-T4:ItisakindoffastEthernettechnologythatcanuse3,4,5typesofunshieldedtwistedpairorshieldedtwistedpair.100Base-T4uses4pairsoftwistedpairs,ofwhichthreepairsareusedtotransmitdataatafrequencyof33MHz,andeachpairworksinhalf-duplexmode.ThefourthpairisusedforCSMA/CDconflictdetection.The8B/6Tencodingmethodisusedinthetransmission,andthesignalfrequencyis25MHz,whichconformstotheEIA586structuredwiringstandard.ItusesthesameRJ-45connectoras10BASE-T,andthemaximumnetworksegmentlengthis100meters.
10 Gigabit Ethernet
Спецификацията за 10 Gigabit Ethernet е включена в допълнителния стандарт IEEE802.3ae на стандарта IEEE802.3. Завършва протокола IEEE802.3 и спецификацията MAC за поддръжка на 10 Gb/s Скоростта на трансфер. yer), 10 Gigabit Ethernet също може да бъде настроен за по-ниска скорост на предаване, като 9,584640 Gb/s (OC-192), което позволява на оборудването 10 Gigabit Ethernet да е съвместимо със синхронната оптична мрежа (SONET) STS -192c формат на предаване.
·10GBASE-SR и 10GBASE-SW поддържат главно късовълнови (850nm) многомодови влакна (MMF), а разстоянието на влакната е 2m до 300m.
10GBASE-SRmainlysupports"darkfiber".Darkfiberreferstoanopticalfiberthathasnolightpropagationandisnotconnectedtoanyequipment.
10GBASE-SWсе използва основно за свързване на SONETоборудване и се използва за отдалечена комуникация на данни.
·10GBASE-LR и 10GBASE-LW поддържат основно дълговълново (1310nm) едномодово влакно (SMF) с разстояние на влакното от 2m до 10 km (около 32 808 фута).
Когато 10GBASE-LW се използва главно за свързване на SONETоборудване,
10GBASE-LR се използва за поддръжка на "тъмно влакно".
·10GBASE-ER и 10GBASE-EW поддържат основно ултра-дълги вълни (1550nm) едномодови влакна (SMF) с разстояние на влакна от 2m до 40km (приблизително 131 233 фута).
10GBASE-EW се използва главно за свързване на SONETоборудване,
10GBASE-E се използва за поддръжка на "тъмно влакно".
·10GBASE-LX4useswavelengthdivisionmultiplexingtechnologytosendsignalsatfourtimestheopticalwavelengthonasinglepairofopticalcables.Thesystemrunsunder1310nmmulti-modeorsingle-modedarkfibermode.Thedesigngoalofthissystemisforthemulti-modefibermodefrom2mto300morthesingle-modefibermodefrom2mto10km.
△Ethernet връзка
Бъдеща тенденция за развитие на мрежата