[mrtg] Gigabit speed, net-snmp, and overflows

[John Haggerty]

I'm trying to track Gigabit traffic on Red Hat 3 Update 5 servers with 
net-snmp (rpm net-snmp-5.0.9-2.30E.15) with mrtg (rpm 
mrtg-2.10.15-1.i386), but even though I've reduced the polling time to 1 
minute, at the highest speeds, the results are inaccurate, I suppose 
because the 32 bit counters overflow in around 30 seconds.

I cannot see how to configure net-snmp to serve up the 64 bit high speed 
counters; for example, cfgmaker says

> cfgmaker --output=/etc/mrtg/phnxbox0.cfg --snmp-options=:::::2 --ifref=ip --global "workdir: /var/www/mrtg/" phnxbox0 

> --base: snmpget public at phnxbox0:::::2:v4only for ifHighSpeed.1 ->  Mb/s
> --base: snmpget public at phnxbox0:::::2:v4only for ifHCInOctets.1 -> 
> --base: check for HighspeedCounters failed ... Dropping back to V1
> --base: snmpget public at phnxbox0:::::2:v4only for ifHighSpeed.2 ->  Mb/s
> --base: snmpget public at phnxbox0:::::2:v4only for ifHCInOctets.2 -> 
> --base: check for HighspeedCounters failed ... Dropping back to V1
> --base: snmpget public at phnxbox0:::::2:v4only for ifHighSpeed.3 ->  Mb/s
> --base: snmpget public at phnxbox0:::::2:v4only for ifHCInOctets.3 -> 
> --base: check for HighspeedCounters failed ... Dropping back to V1
> --base: Writing /etc/mrtg/phnxbox0.cfg

and I agree with it, the commandline snmp tools tell me the same thing. 
  My snmpd.conf is minimal:

> rocommunity public
> 
> interface       eth0     6      1000000000
> interface       eth1     6      1000000000

(the interface lines because snmp didn't seem to get the interface speed 
right, either).

The net-snmp documentation seems to say that it can serve 2c, but I 
can't find the trick.

-- 
John Haggerty
email: haggerty at bnl.gov
voice/fax: 631 344 2286/4592
http://www.phenix.bnl.gov/~haggerty

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