[mrtg] Auto-Discovering IPs of Switch Ports

Steve Shipway s.shipway at auckland.ac.nz
Tue Oct 20 23:22:26 CEST 2009

MRTG just queries what its been told to graph, so it wont get anything like this.

Cfgmaker (the utility that generates the .cfg files for MRTG to use) will not do this by default, but with a bit of work it might be possible to make an interface template for your devices that pulls out the last MAC address seen on a port.  Mapping this to an IP would be a bit more work but not impossible, though you'd probably need something running constantly creating a mapping database?

The way we get around this here is that our Network people set the port description to be the hostname or IP of the device that is attached when they set up the port.  This way I can use the standard settings of cfgmaker to pull out the port description and use that for linking to the required host.


From: mrtg-bounces at lists.oetiker.ch [mailto:mrtg-bounces at lists.oetiker.ch] On Behalf Of Jonathan Mast
Sent: Wednesday, 21 October 2009 4:58 a.m.
To: mrtg at lists.oetiker.ch
Subject: [mrtg] Auto-Discovering IPs of Switch Ports

First of all, let me say that I'm not a networking expert and my terminology is probably a little off.
I have mrtg graphing a cisco switch, and it generates nice little graphs labeled "Traffic Analysis for N -- MY-SWITCH".
This is great except for the fact that I don't have (switch) port to host mapping, all the devices are at a colo.
I did run cfgmaker with each of the available ifref options, all of which didn't help much.
So my question is, can MRTG auto-discover the IP of the connected devices on the switches ports?


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