Zte ZXR10 2900E Series - Page 84

ZXR102900ESeriesCongurationGuide
PortRolePortState
AlternateDiscard
EdgedForward
ProtectionFeatureOverview
BPDUProtectiononaPort
AboundaryportisnotexpectedtoreceiveanyBPDUs.ReceiptofanyBPDUsindicates
afailureinthenetwork.T oavoidthissituation,BPDUprotectioncanbeconguredona
boundaryport.
AfterbeingconguredwithBPDUprotection,ifaportreceivesaBPDU,theportwillbe
shutdownandawarningmessagewillbedisplayed.Thesystemwaitsforsomeseconds
ofuserconguredandthentriestore-opentheport.IfitstillreceivesBPDUs,theportwill
beshutdownagain.Bydoingso,thenetworkcanbeprotectedfrombeingattackedby
abnormalBPDUstomaintainthestabilityofthetopology.
LoopbackProtectiononaPort
Whenanon-designatedportsotherthanportbreaksdownandcannotreceiveanyBPDUs,
STPwilltransittheporttoadesignatedportanditsstatetoForwardingstate,whichleads
toloops.T oavoidthissituation,portloopbackprotectioncanbeconguredonablocked
port.
Afterbeingconguredwithportloopbackprotection,ifablockedportnolongerreceives
anyBPDUs,itwillenterLoop_Inconsistentstate,underwhichnodatawillbeforwarded
fromthisport.WhenitreceivesBPDUsagain,theportwillautomaticallyrecovertoa
blockedport.
RootProtectiononaPort
Afterthenetworkhascompletedthespanningtreecalculation,ifanewswitchisinvolved
andthenumericalvalueforitsbridgeIDislowerthanthatfortherootbridge,thenew
switchwillbecomethenewrootbridgetoreplacetheoldrootbridge,whichcausesthe
entirenetworktorecalculatethespanningtree.Toavoidthissituation,portrootprotection
canbeconguredontheportwhereanewswitchaccessesthenetwork.
Theportrootprotectionfeatureisusedtoprotecttherootbridge.Afterbeingcongured
withrootprotection,ifaportreceivesaBPDUinwhichthenumericalvalueforthebridge
IDislower,theportwillenterRootGuardstatetoavoidspanningtreerecalculation.In
thisstate,nodatawillbeforwardedfromthisport.Oncetheportnolongerreceivesany
BPDUinwhichthenumericalvalueforthebridgeIDislower,itwillgothroughthetransitory
states,thatis,ListeningstateandLearningstate,andnallytransittoForwardingstate.
Therecoveryisautomatic,withoutanyhumanintervention.
ConguringSTP
Inthedefaultconguration,theMSTPonlyhastheinstancewithins_idbeing0.This
instancealwaysexistsanduserscannotmanuallydeleteit.Thisinstanceismappedwith
VLANs1to4094.
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SJ-20130731155059-002|2013-11-27(R1.0)ZTEProprietaryandCondential