Specifications

Configuring STP and RSTP
March 14, 2011 Page 15 of 29
Adjusting the Bridge Hello Time
HellotimeistheintervalatwhichthebridgeorindividualportssendBPDUmessages.Bydefault,
bridgehellomodeisenabled,meaningthedeviceusesasinglebridgeadministrativehellotime.
Adjustthebridgehellotimeasfollows:
1. Checkthestatusofbridgehellomode:
show spantree bridgehellomode
2. Ifnecessary,re‐enablebridgehellomode:
set spantree bridgehellomode enable
3. Setanewhellotimeinterval:
set spantree hello interval
Validintervalvaluesare1–10.
Adjusting Port Hello Times
Youcansetthedevicetouseper‐portadministrativehellotimesbydisablingbridgehellomode
andadjustingthehellotimeintervalforoneormoreportsasfollows:
1. Checkthestatusofbridgehellomode:
show spantree bridgehellomode
2. Ifnecessary,disablebridgehellomode:
set spantree bridgehellomode disable
3. Setanewhellotimeintervalforoneormoreports:
set spantree porthello port-string interval
Validintervalvaluesare10–100
Adjusting the Forward Delay Interval
Whenrapidtransitioningisnotpossible,forwarddelayisusedtosynchronizeBPDUforwarding.
Theforwarddelayintervalistheamountoftimespentlisteningfortopologychangeinformation
afteraninterfacehasbeenactivatedforbridgi ngandbeforeforwardingactuallybegins.This
delayisrequiredbecauseeverydevicemustreceive
informationabouttopologychangesbeforeit
startstoforwardframes.Inaddition,eachportneedstimetolistenforconflictinginformationthat
wouldmakeitreturntoablockingstate.Otherwise,temporarydataloopsmightresult.
Usethiscommandtoadjusttheforwarddelayintervalsetting:
set spantree fwddelay delay
Validdelayvaluesare4–30.
Defining the Maximum Age Time
IfabridgedoesnothearBPDUsfromtherootbridgewithintheinterval(numberofseconds)
specifiedasmaximumagetime,itassumesthatthenetworkhaschangedandrecomputesthe
Caution: Poorly chosen adjustments to bridge and port hello time parameters can have a negative
impact on network performance. It is recommended that you do not change these parameters
unless you are familiar with Spanning Tree configuration and have determined that adjustments are
necessary. Please refer to the IEEE 802.1D specification for guidance.