token ring - ieee 8025 - texas a&m universityieee 8025令牌环-德克萨斯&amp；m大学

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1、TokenRing-IEEE802.5WhattheIEEEstandardcoversHistoryDifferencesbetween802.5and802.3"Physicallayerstandard(giveslinklayerformat)"EssentiallyanIBMstandard'given'totheindustry""GuaranteedresponsePrioritiesControlleddelays"TokenRingHistoryPresentedbyIBMin1982toIE

2、EE802committee.Firstprototypedevelopedin1983inGeneva,Switzerland.CablingSystemwasannouncedin1984.Officiallyannouncedin1985.StandardizedbyIEEEin1985.OnlyoneadoptedbytheIEEE802.5committee.TokenRingTechnologySummaryAccessmethodbywhichnetworkattachmentsgainacces

3、stothecableplantbyacquiringaspecialframecalledthetoken.{Tokenisaspecial24-bitpatternthatcontinuouslycirculatesthering.}TokenRingisabroadcastmedium.{Toreceivedata,adestinationstationperformsanaddressmatch.}Thedestinationstationmerelycopiestheframeasitrepeatsi

4、tbacktothering.Whentheframearrivesbacktothesourcestation,itstripstheframefromtheringandthenreleasesthetoken(4megabitoperationonly).Thetokenisallowedtobereleasedpriortoframereceptionon16-megabitrings.TokenRingoriginallyranat4Mbps.Upgradedin1989to16MbpsMaximum

5、framesizefor4Mbpsis4472.Thisisbasedonlyonthefactastationcannotholdthetokenlongerthan0.010milliseconds.Maximumframesizefor16Mbpsis17,800.TRNFeaturesTrafficusually(alwaysin802.5)unidirectionalRAR(802.5)vsRAT(FDDI)forTokenPassingRecoveryfromlosttokenPrioritiesF

6、rameStructure"datarateof4or16Mbps""oneframeonthenetatatime..."ControllerAttachmenttoaMAUTheIBM8228MAUShieldedorUTPcableLobecablesCableConnectorsTokenRingcontrollerDB-9connectorRJ-11orRJ-45connectorHermaphroditicorRJ-45connectorsonMAUMediafilterforUTPonlyMAUM

7、ediafiltercanbeon-boardMultipleMAUConnectionRinginRingoutMAURinginRingoutMAURinginRingoutMAUType6patchcablesMAUOperationMAUtopviewRelaysLobecablesAllstationsareactiveRinginRingoutMAUbusClosedClosedClosedMAUOperation(InactiveStation)MAUtopviewRelaysLobecables

8、RinginRingoutMAUbusClosedClosedClosedInactivestationTokenRingCableTypesType1Ashieldeddatagradecablewithtwosolidwiretwistedpairs.Availableinindoorandoutdoorversions.Type2AType1indoorcablewithfour