Re: Fast aging of trunk MAC ?

Marko Milivojevic @ 27/01/2010 12:09 -0300 dixit:
>>>> Fa0/22 Desg FWD 200000 128.22 P2p Bound(STP)
>>>> Fa0/24 Root FWD 200000 128.24 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...

I noticed the pre standard message, but as RSPT is holding, I thought
it was just informative.
Yep, this is live but it can whistand some toying off hours.

>
> 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...

That I tried, but nope. Only PVST and .1d
In any case, I don't see what could be causing fast aging of HSRP only.
Read, this sounds like there is a hidden trigger, one I do not know
about and may be missfiring.

My first change was the HSRP group, cause the switch has another HSRP
group in a different vlan. Moging the group id to a new (different MAC)
did not help.

>
> HTH.

Thanks, may be the issue shows up somewhere else some other time.
As someone here said, may be this is abuding GS but I guess that being
exposed to this sort of things is good.

-Carlos
>
> --
> Marko Milivojevic - CCIE #18427
> Senior Technical Instructor - IPexpert
>
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-- 
Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
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