[mrtg] cfgmaker using selective interface.

Mersberger, Robert robert.mersberger at goldenliving.com
Tue Jul 22 23:58:31 CEST 2008

sub interfaces have the same value 32 and will also be equal to
$if-is_wan.  Cannot eliminate $if_type =32 becaues this would also
eliminate se0/0/0

-----Original Message-----
From: Dan [mailto:mrtg at dandoore.com] 
Sent: Tuesday, July 22, 2008 4:17 PM
To: Mersberger, Robert
Cc: mrtg-bounces at lists.oetiker.ch; mrtg at lists.oetiker.ch
Subject: Re: [mrtg] cfgmaker using selective interface.

Mersberger, Robert wrote:
> Is it possible to setup cfgmaker to only poll specific interfaces? 
> Example: I have routers with multiple subinterface but I only want to 
> poll the primary interfaces like fa0/0, fa0/1 and se0/0/0.  I would 
> like to be able to do this with cfgmaker because right now I run 
> cfgmaker then edit the created cfg file and either remove or comment 
> out the interface I do not want to monitor.  This creates problems 
> when I have to recreate the cfg file after a routers configuration 
> changes, like when a port speed in up dated.

There's two ways of doing this that I've used:

1. Use filters with cfgmaker - use something like
'--if-filter=($default_iftype && ($if_is_ethernet || ($if_is_wan &&

2. Use a template with cfgmaker and put a condition on target processing
to match the above criteria with a Perl expression - I do this to filter
out interfaces that I'm not bothered about and tweak parameters on
others so it's more flexible than a filter.

See the template section of the cfgmaker docs and look at 'Template
Example 1' and you can add an extra condition to the section under
if(not $problem_lines) to match or reject interfaces that you wish to
have - I've used a string match on part of the interface name to
explicitly reject things like vlan interfaces and virtual bits that
cfgmaker picks up off some cisco routers.

It's all in http://oss.oetiker.ch/mrtg/doc/cfgmaker.en.html though so
have a dig.


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