[CentOS] Net-SNMP interfaces out of order

Sun Nov 8 19:46:48 UTC 2009
Eduardo Grosclaude <eduardo.grosclaude at gmail.com>

On Sat, Nov 7, 2009 at 9:40 PM, Bob Puff at NLE <bob at nleaudio.com> wrote:

> Hello Centos People,
>
> I have a CentOS 5.3 box that had a total of 5 ethernet cards in it.  It
> functions to share an internet connection with 4 different subnets.  All
> works fine, except I'm noticing that my MRTG traffic graphs are wrong.
> Further digging with snmpwalk reveal that the order of the ethernet
> interfaces changes every time the machine is rebooted to a different order.
>
> For example, I currently see:
>
> IF-MIB::ifDescr.1 = STRING: lo
> IF-MIB::ifDescr.2 = STRING: eth3
> IF-MIB::ifDescr.3 = STRING: eth4
> IF-MIB::ifDescr.4 = STRING: eth0
> IF-MIB::ifDescr.5 = STRING: eth1
> IF-MIB::ifDescr.6 = STRING: eth2
> IF-MIB::ifDescr.7 = STRING: sit0
>
> Why is this not in proper order?  Other servers seem to be ok.  my
> snmpd.conf file has little, if anything as far as config.  Is there
> something I need to put in there for persistence?
>
>
I have found that relying on snmp numbers for interfaces is always tricky.
You may be better off addressing them by 'description' as in

Target[mytarget]: \ppp0:public at localhost

in your mrtg.cfg. Check
http://oss.oetiker.ch/mrtg/doc/mrtg-reference.en.html for the whole story.
HTH

-- 
Eduardo Grosclaude
Universidad Nacional del Comahue
Neuquen, Argentina
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