[c-nsp] PoP Design...

[sthaug at nethelp.no]

> In regards to the PoP design, if I have many access-layer switches under two
> distribution layers.
> 
> 1.	is it recommended to have one of the distribution layers handle the
> VTP management?; Or
> 2.	Make all access layers transparent mode? Or
> 3.	have one access layer be the VTP management?

VTP is evil. There are way too many ways to hang yourself using it.

VTP *may* be suitable for an enterprise setting where you want the same
VLAN config on all switches and have a fairly small number of VLANs.

In a service provider setting we have learned from hard experience that 
you want:

- All the switches independent (no VTP master dependency, and if one switch
gets a problem with its VLAN database it doesn't f*ck up other switches'
VLAN databases).
- Different VLAN config on many switches.
- Explicit control on which VLANs should be allowed on which links. VTP
pruning simply doesn't cut it.

All of these rule out VTP.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no