Network topology [Solved]

John Kemp kemp at
Fri Nov 15 22:41:29 UTC 2013

I know Carlos did a bunch of work to build this
into Netdot, i.e. discover L2, draw usable graphs.

Here's a link to the last NANOG presentation:

John Kemp

On 10/15/08 7:18 PM, Dale W. Carder wrote:
> 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
> -- 
> Dale W. Carder - Network Engineer
> University of Wisconsin / WiscNet

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