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New Member

how to decrease convergence time in STP ?

I read that Cat 3200 cannot support uplink fast.

So, When I connect Cat 6509(uplink fast) with Cat 3200(not uplink fast),

Convergence time is too long and instable.

How can I tunning Cat 3200 connected with Cat6509 supports uplink fast.

Cat 6509 must enable uplink fast . Because 6509 has another STP domain.

Can I have Solution ?

Thanks in advance .....

2 REPLIES
New Member

Re: how to decrease convergence time in STP ?

Uplinkfast is useful in certain scenarios like when you have two links towards the root of the STP and then you lose the primary link as described in the document below

http://www.cisco.com/warp/public/473/51.html

I think you may be confusing uplinkfast to just have fast convergence time.

Enabling uplinkfast on 6500 is not going to help. If you are sure this is non-loop network, try portfast. Please understand this before turning it on. If you don't understand it and enable on looped network, you would cause STP loop.

Another thing you can do is to reduce the diameter and hello intervals. again great caution is needed here

Open a TAC case if needed.

New Member

Re: how to decrease convergence time in STP ?

HI,

Why don't you try tuning STP Timers...this works good also if you're not able to recover so fast (1 second) as UplinkFast (Remember that uplink fast can be implemented ONLY in some network desing)

We have some Gigabit Campus with STP on and timers customized (Forward-delay set to 4 instead of 20) and it works fine with a good convergence time (approx. 5 Sec).

Please as already you know before tuning STP timers study and analyse which potentially impacts could your network have (especially if you connect a switch which has not the same parameters configured!!!)

hth

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