[108668] in North American Network Operators' Group
Re: Network topology [Solved]
daemon@ATHENA.MIT.EDU (Dale W. Carder)
Wed Oct 15 22:19:13 2008
Date: Wed, 15 Oct 2008 21:18:44 -0500
From: "Dale W. Carder" <dwcarder@wisc.edu>
In-reply-to: <48F637F5.9020303@karnaugh.za.net>
To: Colin Alston <karnaugh@karnaugh.za.net>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
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
http://net.doit.wisc.edu/~dwcarder
