[c-nsp] Possible spanning tree issue

[Matthew Huff]

My guess is that you don't have a root switch defined and the new switch became root

On Jun 4, 2013, at 7:41 PM, "Michael Sprouffske" <msprouffske at yahoo.com> wrote:

> This was most definitely a topology change.  Happened when this outage occured.
> 
> 
> 
> 
> ________________________________
> From: Pete Templin <petelists at templin.org>
> To: Michael Sprouffske <msprouffske at yahoo.com> 
> Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net> 
> Sent: Tuesday, June 4, 2013 4:24 PM
> Subject: Re: [c-nsp] Possible spanning tree issue
> 
> 
> On 6/4/13 3:56 PM, Michael Sprouffske wrote:
>> I attached a new switch to the network and it took down our contact
>> center that doesn't touch this switch nor does the phone system.  Is
>> this spanning tree doing this?  I don't see anything in the logs that
>> show a change in spanning tree.
>> 
>> I also had an employee unplug a switch by accident and it took down
>> our contact center.  This switch is all by itself and does not
>> directly touch the phone system nor is it in the path of the phone
>> system.  I feel like this shouldn't have happened.
> 
> You won't see anything in the logs regarding STP changes unless you're 
> running a debug before/during/after and you are logging at the debug 
> level.  Do "sh spann det | inc gy changes" on a switch and see if one or 
> more VLANs had a topology change about the time this event happened.  If 
> it's more recent than that, the commands after the next paragraph may 
> become quite important.
> 
> At this very moment, I would highly suggest that you stop whatever else 
> you're doing and embark on a priority-1 project to assess and define 
> your STP root placement.  I suspect, reading between the lines of your 
> post, that you haven't done much to select where it is, and you're 
> experiencing a change in root placement.  I'd strongly suggest assessing 
> whether any of the following make sense in your environment:
> 
> Global:
> spanning-tree vlan 1-4094 pri 8192
> spanning-tree portfast default
> spanning-tree portfast bpdufilter default
> 
> Interface:
> no spanning-tree portfast
> spanning-tree portfast trunk
> spanning-tree bpduguard enable
> spanning-tree guard root
> 
> pt
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