[c-nsp] spanning-tree problems

[Adam Greene]

> Sounds like you've got some serious issues.  Either it's a really bad
> design, or you're hitting limits or bugs.  Rapid-PVST should reconverge
> damn quickly, but if you're exceeding the number of VLANs it supports
> (platform-dependant), BAD things can happen.  Is the whole network Rapid
> PVST?

>From what I'm able to gather from the customer and from the devices to which
he has granted me access, there are only (3) vlans on the network, but they
*all* span the *entire* campus. The topology is something like this:

2801
|
3750
|            |            |            |            |
3560    3560     3560     3560     Procurve
|            |            |            |            |
2950    2950     2950     2950     wkstns
|            |            |            |
wkstns  wkstns  wkstns   wkstns

It appears that each switch has a trunk connection to its neighbor, on which
all vlans are active.

I'd have to do some investigating to determine whether it's all Rapid PVST,
but judging from the configs on the 3750, the switches were configured using
generic Cisco macros, so I wouldn't be surprised if they are all the same.

I'm not too good at interpreting the debug output, but it looks to me like
spanning-tree is not converging rapidly, which makes me wonder what the
network topology actually is, and whether there are truly some redundant
links and potential loops I am needing to be aware of.

Thanks for your input.

Adam

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