[c-nsp] Maximum spannig tree instances

[sthaug at nethelp.no]

> We have found MST to be mostly pointless...
> 
> "Too much hassle, too little gain"
> 
> But then, we're a service provider environment, and there are hardly
> two VLANs that share the same topology - which maps very poorly to MST
> instances.  At the same time, there is a fairly high dynamic in adding
> and removing VLANs, which is *quite* painful with MST instance 
> mappings...

Depends on how you build your networks. If you build ring structures, I
can see how MST would be useful. We build ring structures but have chosen
the EAPS route instead.

> I just wish more vendors would see the light and implement rapid-PVSTP.

Rapid per VLAN spanning tree has scaling limitations in many environments.
Which is why some people go with MST instead.

Steinar Haug, Nethelp consulting, sthaug at nethelp.no