[c-nsp] Learning L2 switching and spanning tree by doing

[Ross Vandegrift]

On Thu, Apr 10, 2008 at 03:58:15PM -0400, Jeff Kell wrote:
> If you can find a "FM" that discusses converting from, say, default PVST 
> to cross-vendor MST, on a live network across a large campus without an 
> engineer in every closet with a laptop, serial console, and cell phone, 
> let me know :-)

There's no such a book.  I looked long and hard during the last data
center planning phase I went through.

The best document available is the HP Procurve Advanced Traffic
Management Guide for the 2600 and 2800 series fixed-config switches.
It's humble, but much more clearly describes the process than anything
else.  Cisco's MST introduction has very little practical information,
mostly focusing on how things should look - good to know, but doesn't
take you that far.

The reality is worse - vendors have come up with all kinds of gross
misinterpretations of what the MST specification in 802.1Q means.
Of all the vendors I've used, only Cisco gets it right (but only if
your IOS build has the "IEEE Standard MST" instead of the "802.1s
Multiple-Spanning Tree" feature).

For the compatability issues - there is really is no substitute for
getting your hands dirty.  The way I came to understand it is to take
a few different layer 2 switches from a few vendors, set them up, and
troubleshoot it until it works the way you want.

This is somewhat easier if you don't have to do it on your own dime. :)

-- 
Ross Vandegrift
ross at kallisti.us

"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
	--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37