[c-nsp] Troubleshooting vtp pruning

[Victor Sudakov]

Ian Henderson wrote:
> On 10 Nov 2014, at 4:02 pm, Victor Sudakov <vas at mpeks.tomsk.su> wrote:
> > Port        Vlans in spanning tree forwarding state and not pruned
> > Gi0/1       1,3,10,20,22,24-28,30,32,34,36,200,308
> > Gi0/2       1,3,10,20,22,24-28,30,32,34,36,200,308
> 
> 
> VTP won???t prune because you have dual uplinks. 

What is dual uplinks? My topology is linear. Gi0/1 goes to the South
neighbor in the chain, and Gi0/2 goes to the North neighbor in the
chain, like in the attached screenshot.


> It doesn???t know
> that they both go to the core layer. 

They both ARE the core layer. 

> One could be a downstream
> switch as far as VTP is concerned.

Sometimes there is more than one link between two neighboring
switches, STP takes care of them. Other than that, the topology is
linear.  I can even make it totally linear by manually disabling a
couple of redundant links.

I expect that if a vlan is being used only on one or two switches on
one end of the chain, it should be pruned from the rest of the chain.
But it is not happening.

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov at sibptus.tomsk.ru