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Re: Network topology [Solved]

  • From: Dale W. Carder
  • Date: Wed Oct 15 22:19:08 2008

On Oct 15, 2008, at 1:35 PM, Colin Alston wrote:

On 2008/10/15 06:29 PM Colin Alston wrote:
Is there any kind of cunning trick to detect standard layer2 switches along a path without stuff like STP?

Apparently there isn't. Lots of people mentioned other tools, the problem there is they have one thing in common which is polling SNMP. I think it scales badly in general.

What is your reasoning behind this claim? I would claim quite the opposite compared to CLI or TL1.

Maybe there should be something (I mean like, someone should come up with a standard :P) to trace switches in a path

I've written a cruddy script that given a seed bridge, scrapes L2 information obtained via CDP (I guess it could do LLDP, too) and does a breadth-first search through a network. Then I just dump that into gnuplot format. Getting the data is easy compared to visualization.

A coworker of mine has written script to ask Rapid-STP speaking
switches about their current topology and builds a graph again
in gnuplot format.

A more challenging approach would be to scrape the mac forwarding
tables and stitch things together.  This would have to be done
per-vlan.  I think this approach (or similar) might be done by
Openview's L2 featureset.


Dale W. Carder - Network Engineer
University of Wisconsin / WiscNet