[c-nsp] backup with STP

[David J. Hughes]

I've been trying to delve back into memory to remember all the 
intricate bits and pieces of MST (it's been quite a while).  In the 
context of the original question, one of the driving points for the 
posters decision making was support for legacy dot1D devices.  Now, you 
guys are far more familiar with MST than I am these days so I'm sure 
you can clarify this point.

 From my memory, all dot1D devices were held in a "virtual region" 
outside MST's IST instance.  In this situation is a dot1D BPDU 
forwarded into the IST and as such broadcasted to all STP instances or 
is there another STP instance outside the IST for the dot1D devices?

Like I said, it's been a while but I thought legacy dot1D support was a 
weak point in MST.  RPVST+ naturally doesn't suffer from this sort of 
problem.


David
...


On 30/09/2005, at 3:39 AM, <lists at hojmark.org> wrote:

>> True, I'm looking at it from a datacentre perspective with
>> hundreds, not thousands of vlans.
>
> Good...
>
> As long as you don't have small, cheap switches like the Catalyst
> 3750 (or smaller), which will only do 128 STP instances (or less)
> then you probably don't need MST...
>
> Many of my customers use small switches, which won't do many
> STPs. And even those that use more capable equipment could easily
> benefit from the lower CPU utilization that you get when you only
> need to calculate a couple of spanning trees.
>
> -A
>