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首页 802.3-2008 section 2.pdf

802.3-2008 section 2.pdf

802.3-2008 section 2.pdf

上传者: 阿飞 2011-12-04 评分 5 0 144 20 656 暂无简介 简介 举报

简介:本文档为《802.3-2008 section 2pdf》,可适用于IT/计算机领域,主题内容包含IEEEStandardforInformationtechnologyTelecommunicationsandinformationexchan符等。

IEEEStandardforInformationtechnologyTelecommunicationsandinformationexchangebetweensystemsLocalandmetropolitanareanetworksSpecificrequirementsPart:CarrierSenseMultipleAccesswithCollisionDetection(CSMACD)accessmethodandPhysicalLayerspecificationsSECTIONTWO:ThissectionincludesClausethroughClauseandAnnexAthroughAnnexEIntroductiontoMbsbasebandnetworks,typeBASETOverviewBASETcouplestheIEEECSMACDMACwithafamilyofMbsPhysicalLayersWhiletheMACcanbereadilyscaledtohigherperformancelevels,newPhysicalLayerstandardsarerequiredforMbsoperationTherelationshipsbetweenBASET,theexistingIEEE(CSMACDMAC),andtheISOIECOpenSystemInterconnection(OSI)referencemodelisshowninFigure–BASETusestheexistingIEEEMAClayerinterface,connectedthroughaMediaIndependentInterfacelayertoaPhysicalLayerentity(PHY)sublayersuchasBASET,BASETX,orBASEFXBASETextendstheIEEEMACtoMbsThebitrateisfaster,bittimesareshorter,packettransmissiontimesarereduced,andcabledelaybudgetsaresmallerallinproportiontothechangeinbandwidthThismeansthattheratioofpacketdurationtonetworkpropagationdelayforBASETisthesameasforBASETReconciliationSublayer(RS)andMediaIndependentInterface(MII)TheMediaIndependentInterface(Clause)providesaninterconnectionbetweentheMediaAccessControl(MAC)sublayerandPhysicalLayerentities(PHY)andbetweenPHYLayerandStationManagement(STA)entitiesThisMIIiscapableofsupportingbothMbsandMbsdataratesthroughfourbitwide(nibblewide)transmitandreceivepathsTheReconciliationsublayerprovidesamappingbetweenthesignalsprovidedattheMIIandtheMACPLSservicedefinitionCopyrightIEEEAllrightsreservedIEEEStdREVISIONOFIEEEStd:PhysicalLayersignalingsystemsThefollowingportionofthisstandardspecifiesafamilyofPhysicalLayerimplementationsTypicallyBASETX(Clausesand)usestwopairsofCategorybalancedcablingasdefinedbyISOIEC,BASEFX(Clausesand)usestwomultimodefibersThereareanumberofotherPHYtypesandtheirassociatedmediaRepeaterRepeatersets(Clause)areanintegralpartofanyBASETnetworkwithmorethantwoDTEsinacollisiondomainTheyextendthephysicalsystemtopologybycouplingtwoormoresegmentsMultiplerepeatersarepermittedwithinasinglecollisiondomaintoprovidethemaximumpathlengthAutoNegotiationAutoNegotiation(Clause)providesalinkeddevicewiththecapabilitytodetecttheabilities(modesofoperation)supportedbythedeviceattheotherendofthelink,determinecommonabilities,andconfigureforjointoperationAutoNegotiationisperformedoutofbandusingapulsecodesequencethatiscompatiblewiththeBASETlinkintegritytestsequencePRESENTATIONAPPLICATIONSESSIONTRANSPORTNETWORKDATALINKPHYSICALOSIREFERENCEMODELLAYERSLANCSMACDLAYERSLLC(LOGICALLINKCONTROL)MACMEDIAACCESSCONTROLPMAHIGHERLAYERSMDI=MEDIUMDEPENDENTINTERFACEMII=MEDIAINDEPENDENTINTERFACEPCS=PHYSICALCODINGSUBLAYER*MIIisoptionalforMbsDTEsandforMbssystemsandisnotspecifiedforMbssystemsPMA=PHYSICALMEDIUMATTACHMENTPHYPHY=PHYSICALLAYERDEVICE*MIIMDIPCS**PMDPMD=PHYSICALMEDIUMDEPENDENT**PMDisspecifiedforBASEXonlyBASETdoesnotusethislayerRECONCILIATION**PMDPHYMDIPMAPCSBASETRepeaterBaseband**PMDPHYMDIPMAMbslinksegmentPCSMEDIUMMbslinksegmentMEDIUMUseofMIIbetweenPCSandBasebandRepeaterUnitisoptional***AUTONEG***AUTONEG***AUTONEG***AUTONEGisoptionalBASETBasebandRepeaterUnitFigure–ArchitecturalpositioningofBASETSetOROTHERMACCLIENTCopyrightIEEEAllrightsreservedIEEECSMACDStdManagementManagedobjects,attributes,andactionsaredefinedforallBASETcomponents(Clause)ThisclauseconsolidatesallIEEEmanagementspecificationssothatMbs,MbsorMbsagentscanbemanagedbyexistingMbsonlynetworkmanagementstationswithlittleornomodificationtotheagentcodeReferencesSeeDefinitionsSeeAbbreviationsSeeStatediagramsStatediagramstakeprecedenceovertextTheconventionsofareadopted,withthefollowingextensionsActionsinsidestateblocksTheactionsinsideastateblockexecuteinstantaneouslyActionsinsidestateblocksareatomic(ie,uninterruptible)Afterperformingalltheactionslistedinastateblockonetime,thestateblockthencontinuouslyevaluatesitsexitconditionsuntiloneissatisfied,atwhichpointcontrolpassesthroughatransitionarrowtothenextblockWhilethestateawaitsfulfillmentofoneofitsexitconditions,theactionsinsidedonotimplicitlyrepeatThecharacters•andbracketarenotusedtodenoteanyspecialmeaningValidstateactionsmayincludeindicationandrequestmessagesNoactionsaretakenoutsideofanystateblockStatediagramvariablesOnceset,variablesretaintheirvaluesaslongassucceedingblockscontainnoreferencestothemSettingtheparameterofaformalinterfacemessageassuresthat,onthenexttransmissionofthatmessage,thelastparametervaluesetwillbetransmittedTestingtheparameterofaformalinterfacemessagesteststhevalueofthatmessageparameterthatwasreceivedonthelasttransmissionofsaidmessageMessageparametersmaybeassigneddefaultvaluesthatpersistuntilthefirstreceptionoftherelevantmessageCopyrightIEEEAllrightsreservedIEEEStdREVISIONOFIEEEStd:StatetransitionsThefollowingtermsarevalidtransitionqualifiers:a)Booleanexpressionsb)Aneventsuchastheexpirationofatimer:timerdonec)Aneventsuchasthereceptionofamessage:PMAUNITDATAindicationd)Anunconditionaltransition:UCTe)Abranchtakenwhenotherexitconditionsarenotsatisfied:ELSEAnyopenarrow(anarrowwithnosourceblock)representsaglobaltransitionGlobaltransitionsareevaluatedcontinuouslywheneveranystateisevaluatingitsexitconditionsWhenaglobaltransitionbecomestrue,itsupersedesallothertransitions,includingUCT,returningcontroltotheblockpointedtobytheopenarrowOperatorsThestatediagramoperatorsareshowninTable–Table–StatediagramoperatorsCharacterMeaningBooleanANDBooleanORBooleanXOR!BooleanNOT<LessthanLessthanorequalto=Equals(atestofequality)NotequalsGreaterthanorequalto>Greaterthan()IndicatesprecedenceAssignmentoperatorIndicatesmembershipIndicatesnonmembership|CatenateELSENootherstateconditionissatisfiedCopyrightIEEEAllrightsreservedIEEECSMACDStdProtocolimplementationconformancestatement(PICS)proformaIntroductionThesupplierofaprotocolimplementationthatisclaimedtoconformtoanyMbsportionofthisstandardshallcompleteaprotocolimplementationconformancestatement(PICS)proformaAcompletedPICSproformaisthePICSfortheimplementationinquestionThePICSisastatementofwhichcapabilitiesandoptionsoftheprotocolhavebeenimplementedAPICSisincludedattheendofeachclauseasappropriateThePICScanbeusedforavarietyofpurposesbyvariousparties,includingthefollowing:a)Asachecklistbytheprotocolimplementor,toreducetheriskoffailuretoconformtothestandardthroughoversightb)Asadetailedindicationofthecapabilitiesoftheimplementation,statedrelativetothecommonbasisforunderstandingprovidedbythestandardPICSproforma,bythesupplierandacquirer,orpotentialacquirer,oftheimplementationc)Asabasisforinitiallycheckingthepossibilityofinterworkingwithanotherimplementationbytheuser,orpotentialuser,oftheimplementation(notethat,whileinterworkingcanneverbeguaranteed,failuretointerworkcanoftenbepredictedfromincompatiblePICS)d)Asthebasisforselectingappropriatetestsagainstwhichtoassesstheclaimforconformanceoftheimplementation,byaprotocoltesterAbbreviationsandspecialsymbolsThefollowingsymbolsareusedinthePICSproforma:Mmandatoryfieldfunction!negationOoptionalfieldfunctionO<n>optionalfieldfunction,butatleastoneofthegroupofoptionslabeledbythesamenumeral<n>isrequiredO<n>optionalfieldfunction,butoneandonlyoneofthegroupofoptionslabeledbythesamenumeral<n>isrequiredXprohibitedfieldfunction<item>:simplepredicatecondition,dependentonthesupportmarkedfor<item><item>*<item>:ANDpredicatecondition,therequirementmustbemetifbothoptionalitemsareimplementedInstructionsforcompletingthePICSproformaThefirstpartofthePICSproforma,ImplementationIdentificationandProtocolSummary,istobecompletedasindicatedwiththeinformationnecessarytoidentifyfullyboththesupplierandtheimplementationThemainpartofthePICSproformaisafixedformatquestionnairedividedintosubclauses,eachcontainingagroupofitemsAnswerstothequestionnaireitemsaretobeprovidedintherightmostcolumn,eitherbysimplymarkingananswertoindicatearestrictedchoice(usuallyYes,No,orNotApplicable),orbyenteringavalueorasetorrangeofvalues(Notethattherearesomeitemswheretwoormorechoicesfromasetofpossibleanswerscanapplyallrelevantchoicesaretobemarked)EachitemisidentifiedbyanitemreferenceinthefirstcolumnthesecondcolumncontainsthequestiontobeansweredthethirdcolumncontainsthereferenceorreferencestothematerialthatspecifiestheiteminthemainbodyofthestandardthesixthcolumncontainsvaluesandorcommentspertainingtothequestionCopyrightIEEEAllrightsreservedIEEEStdREVISIONOFIEEEStd:tobeansweredTheremainingcolumnsrecordthestatusoftheitemswhetherthesupportismandatory,optionalorconditionalandprovidethespacefortheanswersThesuppliermayalsoprovide,orberequiredtoprovide,furtherinformation,categorizedaseitherAdditionalInformationorExceptionInformationWhenpresent,eachkindoffurtherinformationistobeprovidedinafurthersubclauseofitemslabeledA<i>orX<i>,respectively,forcrossreferencingpurposes,where<i>isanyunambiguousidentificationfortheitem(eg,simplyanumeral)therearenootherrestrictionsonitsformatorpresentationAcompletedPICSproforma,includinganyAdditionalInformationandExceptionInformation,istheprotocolimplementationconformancestatementfortheimplementationinquestionNotethatwhereanimplementationiscapableofbeingconfiguredinmorethanoneway,accordingtotheitemslistedunderMajorCapabilitiesOptions,asinglePICSmaybeabletodescribeallsuchconfigurationsHowever,thesupplierhasthechoiceofprovidingmorethanonePICS,eachcoveringsomesubsetoftheimplementation’sconfigurationcapabilities,ifthatwouldmakepresentationoftheinformationeasierandclearerAdditionalinformationItemsofAdditionalInformationallowasuppliertoprovidefurtherinformationintendedtoassisttheinterpretationofthePICSItisnotintendedorexpectedthatalargequantitywillbesupplied,andthePICScanbeconsideredcompletewithoutanysuchinformationExamplesmightbeanoutlineofthewaysinwhicha(single)implementationcanbesetuptooperateinavarietyofenvironmentsandconfigurationsorabriefrationale,basedperhapsuponspecificapplicationneeds,fortheexclusionoffeaturesthat,althoughoptional,arenonethelesscommonlypresentinimplementationsReferencestoitemsofAdditionalInformationmaybeenterednexttoanyanswerinthequestionnaire,andmaybeincludedinitemsofExceptionInformationExceptionalinformationItmayoccasionallyhappenthatasupplierwillwishtoansweranitemwithmandatoryorprohibitedstatus(afteranyconditionshavebeenapplied)inawaythatconflictswiththeindicatedrequirementNopreprintedanswerwillbefoundintheSupportcolumnforthisinstead,thesupplierisrequiredtowriteintotheSupportcolumnanX<i>referencetoanitemofExceptionInformation,andtoprovidetheappropriaterationaleintheExceptionitemitselfAnimplementationforwhichanExceptionitemisrequiredinthiswaydoesnotconformtothisstandardNotethatapossiblereasonforthesituationdescribedaboveisthatadefectinthestandardhasbeenreported,acorrectionforwhichisexpectedtochangetherequirementnotmetbytheimplementationConditionalitemsThePICSproformacontainsanumberofconditionalitemsTheseareitemsforwhichboththeapplicabilityoftheitemitself,anditsstatusifitdoesapplymandatory,optional,orprohibitedaredependentuponwhetherornotcertainotheritemsaresupportedIndividualconditionalitemsareindicatedbyaconditionalsymboloftheform“<item>:<s>”intheStatuscolumn,where“<item>”isanitemreferencethatappearsinthefirstcolumnofthetableforsomeotheritem,and“<s>”isastatussymbol,M(Mandatory),O(Optional),orX(NotApplicable)CopyrightIEEEAllrightsreservedIEEECSMACDStdIftheitemreferredtobytheconditionalsymbolismarkedassupported,then)theconditionalitemisapplicable,)itsstatusisgivenby“<s>”,and)thesupportcolumnistobecompletedintheusualwayOtherwise,theconditionalitemisnotrelevantandtheNotApplicable(NA)answeristobemarkedEachitemwhosereferenceisusedinaconditionalsymbolisindicatedbyanasteriskintheItemcolumnRelationofBASETtootherstandardsSuitableentriesforTableGofISOIEC,AnnexGwouldbeasfollows:a)WithinthesectionBalancedCablingLinkClassC(specifieduptoMHz):CSMACDBASETISOIECDADCSMACDBASET*ISOIECDADb)WithinthesectionOpticalLink:CSMACDBASEFXISOIECDADc)WithinthesectionBalancedCablingLinkClassD(defineduptoMHz):CSMACDBASETXISOIECDAD*TosupportBASETapplications,ClassClinksshallhaveaNEXTvalueofatleastdBinexcessofthevaluesspecifiedinSuitableentriesforTableGofISOIEC,AnnexG,wouldbeasfollows:aIEEEimposesadditionalrequirementsonpropagationdelayAsuitableentryforTableGofISOIEC,AnnexG,wouldbeasfollows:BalancedcablingPerformancebasedcablingperClauseperClauses,,andClassAClassBClassCClassDCatΩCatΩCatΩCatΩCatΩCatΩΩΩΩΩΩΩΩΩΩΩΩΩΩ:BASETIaIIIIIIIIaII:BASETIaIIIIIIaI:BASETXIaIaIaIaFibreOpticallinkperClauseper,,andHorizontalBuildingbackboneCampusbackbonemmMMFmmMMFmmMMFmmMMFmmMMFmmMMFmmMMFmmMMFmmMMFmmMMFmmMMFmmMMF:BASEFXNINININICopyrightIEEEAllrightsreservedIEEEStdREVISIONOFIEEEStd:MACdelayconstraints(exposedMII)BASETmakesthefollowingassumptionsaboutMACperformanceTheseassumptionsapplytoanyMACoperatinginhalfduplexmodewithanexposedMIITable–MACdelayassumptions(exposedMII)SublayermeasurementpointsEventMin(bits)Max(bits)InputtimingreferenceOutputtimingreferenceMACMIIMACtransmitstarttoTXENsampledTXCLKrisingCRSasserttoMACdetectCRSdeasserttoMACdetectCRSasserttoTXENsampled(worstcasenondeferredtransmit)TXCLKrisingCOLasserttoMACdetectCOLdeasserttoMACdetectCOLasserttoTXD=Jamsampled(worstcasecollisionresponse)TXCLKrisingfirstnibbleofjamCopyrightIEEEAllrightsreservedIEEECSMACDStdReconciliationSublayer(RS)andMediaIndependentInterface(MII)OverviewThisclausedefinesthelogical,electrical,andmechanicalcharacteristicsfortheReconciliationSublayer(RS)andMediaIndependentInterface(MII)betweenCSMACDmediaaccesscontrollersandvariousPHYsFigure–showstherelationshipoftheReconciliationsublayerandMIItotheISOIECOSIreferencemodelThepurposeofthisinterfaceistoprovideasimple,inexpensive,andeasytoimplementinterconnectionbetweenMediaAccessControl(MAC)sublayersandPHYsfordatatransferatMbsandMbs,andbetweenStationManagement(STA)andPHYentitiessupportingdatatransferatMbsorabove(see)Thisinterfacehasthefollowingcharacteristics:a)ItiscapableofsupportingMbsandMbsratesfordatatransfer,andmanagementfunctionsforPHYssupportingdatatransferatMbsorabove(see)b)Dataanddelimitersaresynchronoustoclockreferencesc)Itprovidesindependentfourbitwidetransmitandreceivedatapathsd)ItusesTTLsignallevels,compatiblewithcommondigitalCMOSASICprocessese)Itprovidesasimplemanagementinterfacef)Itiscapableofdrivingalimitedlengthofshieldedcableg)ItprovidesfullduplexoperationFigure–MIIrelationshiptotheISOIECOpenSystemsInterconnection(OSI)referencemodelandtheIEEECSMACDLANmodelPRESENTATIONAPPLICATIONSESSIONTRANSPORTNETWORKDATALINKPHYSICALOSIREFERENCEMODELLAYERSLANCSMACDLAYERSAUIMIIMDIMDI=MEDIUMDEPENDENTINTERFACEMII=MEDIAINDEPENDENTINTERFACEMDIMbs,GbsMbsMEDIUMPLSPMAPMAPCSPMDHIGHERLAYERSLLC(LOGICALLINKCONTROL)OROTHERMACCLIENTMACCONTROL(OPTIONAL)MIIGMIIMACMEDIAACCESSCONTROLRECONCILIATIONPLS=PHYSICALLAYERSIGNALINGPHYPMA=PHYSICALMEDIUMATTACHMENTPHY=PHYSICALLAYERDEVICEPMD=PHYSICALMEDIUMDEPENDENTAUI=ATTACHMENTUNITINTERFACEGMII=GIGABITMEDIAINDEPENDENTINTERFACEMAU=MEDIUMATTACHMENTUNITMAUPCS=PHYSICALCODINGSUBLAYERRECONCILIATIONMEDIUMCopyrightIEEEAllrightsreservedIEEEStdREVISIONOFIEEEStd:Summaryofmajorconceptsa)Eachdirectionofdatatransferisservicedwithseven(makingatotalof)signals:Data(afourbitbundle),Delimiter,Error,andClockb)TwomediastatussignalsareprovidedOneindicatesthepresenceofcarrier,andtheotherindicatestheoccurrenceofacollisionc)Amanagementinterfacecomprisedoftwosignalsprovidesaccesstomanagementparametersandservicesd)TheReconciliationsublayermapsthesignalsetprovidedattheMIItothePLSservicedefinitionspecifiedinClauseApplicationThisclauseappliestotheinterfacebetweenMACsublayerandPHYs,andbetwee

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