Specifications

Understanding and Configuring Loop Protect
March 14, 2011 Page 25 of 29
Configuring Loop Protect
ThissectionprovidesinformationaboutLoopProtectconfiguration:
• EnablingorDisablingLoopProtect(page25)
• SpecifyingLoopProtectPartners(page25)
• SettingtheLoopProtectEventThresholdandWindow(page25)
• EnablingorDisablingLoopProtectEventNotifications(page26)
• SettingtheDisputedBPDUThreshold(page26)
• MonitoringLoopProtectStatus
andSettings(page26)
Enabling or Disabling Loop Protect
Bydefault,LoopProtectisdisabledonallports.Usethiscommandtoenable(or,ifdesired,
disable)thefeatureononeormoreports:
set spantree lp port-string {enable | disable} [sid sid]
IfnoSIDisspecified,SID0isassumed.
ThiscommandtakesprecedenceoverperportSTPenable/disablestate(portAdmin).Normally,
portAdmindisabledwouldcauseaporttogoimmediatelytoforwarding.IfLoopProtectis
enabled,thatportshouldgotolisteningandremainthere.
Specifying Loop Protect Partners
Bydefault,eachportisnotsetasaLoopProtectcapablepartner.IftheportissetasaLoopProtect
capablepartner(true),thenthefullfunctionalityoftheLoopProtectfeatureisused.Ifthevalueis
false,thenthereissomeambiguityastowhetheranActive
Partnertimeout isdueto aloop
protectioneventorisanormalsituationduetothefactthatthepartnerportdoesnottransmit
AlternateAgreementBPDUs.Therefore,aconserva tiveapproachistakeninthatdesignatedports
willnotbeallowedtoforwardunlessreceivingagreementsfromaport
withrootrole.Thistypeof
timeoutwillnotbeconsideredaloopprotectionevent.Loopprotectionismaintainedbykeeping
theportfromforwarding,butsincethisisnotconsideredaloopevent,itwillnotbefactoredinto
lockingtheport.
UsethiscommandtosettheLoopProtect
partnerstateononeormoreports:
set spantree lpcapablepartner port-string {true | false}
Setting the Loop Protect Event Threshold and Window
TheLoopProtecteventthresholdisaglobalintegervariablethatprovidesprotectioninthecaseof
intermittentfailures.Thedefaultvalueis3.Iftheeventcounterreachesthethresholdwithina
givenperiod(theeventwindow),thentheportforthegivenSIDbecomeslocked(thatis,held
indefinitely
intheblockingstate).Ifthe thresholdis0,theportsareneverlocked.
UsethiscommandtosettheLoopProtecteventthreshold:
set spantree lpthreshold value
Note: The Loop Protect enable/disable settings for an MSTI port should match those for the CIST
port.