Specifications

Configuring and Managing STP Fast Convergence Features
13-8 Configuring and Managing Spanning Tree Protocol
Backbone Fast Convergence
Backbonefastconvergenceacceleratesaport’srecoveryfollowingthefailureofanindirectlink.
Normally,whenaforwardinglinkfails,abridgethatisnotdirectlyconnectedtothelinkdoesnot
detectthelinkchangeuntilthemaximumagetimerexpires.Backbonefastconvergenceenables
theRoamAboutSwitchtolisten
forbridgeprotocoldataunits(BPDUs)sentbyadesignated
bridgewhenthedesignatedbridge’slinktotherootbridgefails.Theswitchimmediatelyverifies
whetherBPDUinformationstoredonaportisstillvalid.Ifnot,thebridgeimmediatelystartsthe
listeningstageontheport.
Uplink Fast Convergence
Uplinkfastconvergenceenablesaswitchthathasredundantlinkstothenetworkcoreto
immediatelychangethestateofabackuplinktoforwardingiftheprimarylinktotherootfails.
Uplinkfastconvergencebypassesthelisteningandlearningstatestoimmediatelyenterthe
forwardingstate.
Configuring Port Fast Convergence
Toenableordisableportfastconvergence,usethefollowingcommand:
set spantree portfast port port-list {enable | disable}
Example
Toenableportfastconvergenceonports9,11,and13,typethefollowingcommand:
RBT-8100# set spantree portfast port 9,11,13 enable
success: change accepted.
Note: If you plan to use the backbone fast convergence feature, you must enable it on all the bridges
in the spanning tree.
Note: The uplink fast convergence feature is applicable to bridges that are acting as access
switches to the network core (distribution layer) but are not in the core themselves. Do not enable
the feature on RoamAbout Switches that are in the network core.