[c-nsp] Spanning Tree Max VLAN's 35xx

[Laura Kristoff]

sthaug at nethelp.no wrote:
>>> What is the best way to filter out VLAN's headed to the device?  If I put
>>> VLAN allow lists on the uplink ports does that do anything to limit the STP
>>> instances or is all of that being carried by VTP to the switch regardless of
>>> filters?  What about VTP Pruning on the VTP server?
>>>       
>> We ran into this a lot.  What we finally did is to change all of our
>> switches to  transparent mode (so basically disabled VTP).  You'd
>> still have to go and manually delete all the unused VLANs after you make
>> the change.  It may not work for you if you like the automation provided
>> by VTP, but we prefer to just manually create the vlans we need on our
>> switches. 
>>     
>
> [...] We look at
> VTP as both unusable (because it forces the same VLANs on all switches)
> and dangerous (a screwup on the VTP master can have major impact).[...]

That's a good point about the "danger" aspect of it. We've got bitten by 
that before.  In fact even a switch configured as a VTP client  can 
overwrite a  switch configured as a VTP server if the revision number on 
the client happens to be higher (like when it was used in the lab and 
underwent a bunch of changes to the vlan configuration).   Very scary.