Re: Fast aging of trunk MAC ?

>>> Fa0/22 B B B B B B B Desg FWD 200000 B B 128.22 B P2p Bound(STP)
>>> Fa0/24 B B B B B B B Root FWD 200000 B B 128.24 B P2p Bound(RSTP) Pre-STD-Rx
>>
>> What is connected to these two ports? Also, where is 7200b connected
>> to in the diagram above?
>
> Fa0/22 is the 2950 of the diagram.
> Fa0/24 is the "L2net", another switch (not cisco) connecting eventually
> to 7200b among other things.

I would have expected other way round, to be honest. Whatever is
connected to 24 speaks pre-standard RSTP (Cisco's). While I have not
seen it cause any issues like those you have described, you should
address this issue by configuring your 3550 to speak Cisco's
pre-standard 802.1s on that port. The command to use is "spanning-tree
mst pre-standard". Also, you need to either bounce the port, or clear
learned protocols using "clear spanning-tree detected-protocols". The
funny thing here is that Cisco doesn't really say what EXACTLY can go
wrong if you don't do this, they simply state that you SHOULD do this.
I suppose you hit one of those "why's". It would be interesting to try
and recreate the problem and investigate a bit deeper. I'm afraid
we're dealing with the live environment in your case and that it may
not be doable...

OK, another thing from your output, Fa0/22 is running the 802.1d.
Can't you migrate that switch to 802.1w/802.1s? If it is indeed 2950
connected to that port, I seem to recall it does run MST in some shape
and form...

HTH.

--
Marko Milivojevic - CCIE #18427
Senior Technical Instructor - IPexpert
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