[c-nsp] spantree pvst and mst

[Shaun]

> VTP Pruning is probably working just fine. It's just not meant
> to solve that particular problem. It'll only prune back flooding
> for non-active VLANs, not stop the VLAN from being created.
>
> See http://tinyurl.com/9rhf7

Maybe my understanding of VTP pruning was wrong.  I know VTP pruning did 
what was said in that url above but i also though it kept the client 
switches from seeing vlans that where not assigned to ports on that switch. 
the 3750's i think support 4000 somthing vlans and the 2950's only support 
1024 if i remember correctly.  I always though vtp pruning would protect the 
2950's from hitting that limit when say my 3750 has 2000 vlans on it. 
(meaning the 2950 only would see say 50 vlans, when theirs actually 2000). 
I know a sh vlan will show all vlans on a client but i figured thats just 
being looked up from the vtp server...

Also when vtp pruning is enabled, i have diffrent vlans active when i do a 
sh int trunk on the 3750 and 2950.  I had a diffrent post about this on nsp, 
here's a example of what that shows from each end.

2950G
    Port        Vlans in spanning tree forwarding state and not pruned
    Fa0/1       1-2,20,50,60-61,95-119,121-153,155-158

3750
    Port        Vlans in spanning tree forwarding state and not pruned
    Fa1/0/13    1-2,60,97-99,115,120,122,133,137-138,141-142,144,153

Shoudnt both sides report the same vlans?  This is happening on all my other 
trunked ports also.


> If you have too many VLANs for a 2950 to handle, simply don't
> send it that many VLANs with VTP. Set the switch to transparent
> mode instead.

VTP makes it easy seeing how i dont have to create/remove vlans on the 
2950's also but i guess when that time comes if thats my only option i guess 
i'll have to go that route.

> If you want to change from pVST+ to MSTP, you'd better do it in
> the whole L2 domain. It is possible to mix the two, but it can
> get kind of tricky. If you do, keep the root inside the MSTP
> region, not outside it.

I planned on making all 2950's MSTP to solve the problem with hitting the 
STP interface limit of 64 on the 2950's (course my understanding was that 
pruning would make it only show ~50 vlans or so active and i'd only have 50 
STP interfaces).  the 3750 is doing routing so i assume your not saying i 
should change my 3750 to MSTP?  I also dont understand what you mean by keep 
the root inside MSTP region.

Thanks for your help so far, appreciate it!


~Shaun