[108659] in North American Network Operators' Group
Re: Network topology
daemon@ATHENA.MIT.EDU (Ian Mason)
Wed Oct 15 17:05:41 2008
In-Reply-To: <48F61FC3.2080602@karnaugh.za.net>
From: Ian Mason <nanog@ian.co.uk>
Date: Wed, 15 Oct 2008 22:05:14 +0100
To: Colin Alston <karnaugh@karnaugh.za.net>
Cc: NANOG list <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On 15 Oct 2008, at 17:52, Colin Alston wrote:
> On 2008/10/15 06:29 PM Bill Woodcock wrote:
>> InterMapper. http://dartware.com/network_monitoring_products/
>> intermapper/index.html
>> -Bill
>
> Whoa, quite a serious looking piece of software. Will check it out.
>
> Was kinda hoping to write my own software though, but perhaps I can
> craftily learn something from it :)
>
If you have SNMP access pull:-
1) Is it a bridge or a router?
2) ARP Table
3) MAC forwarding table
4) Interfaces with MAC and IP addresses
5) Netmasks
from each such router or bridge in the network. Use the information
from one to help you discover the
others recursively. Have a termination condition that stops this
process walking off your network and
attempting to discover the whole Internet.
That's enough to figure out both logical and physical topology.
Without SNMP (or similar) access it's nigh impossible to figure out.
If you only have access to a subset
of the routers and bridges in the network you MAY have enough to
figure out the topology - 50% is enough
if it's the right 50%.
Ian
