[mrtg] MRTG and SNMPv2 64 bit counters

Giuseppe Larosa giuseppe.larosa at cselt.it
Thu Oct 28 10:37:42 MEST 1999

For monitoring heavy loaded high speed links like 155 Mbps ATM links the

usage of the common byte counters  ifInOctets and ifOutOctets can lead
to mistakes.
( the full path is
These variables are 32 bit integers and it takes less than 5 minutes
for a 155 Mbps full loaded  interface to drive these counters to wrap.
We have found other variables in the MIB ifMIB that are 64 bit counters.

They are ifHCInOctets and  ifHCOutOctets and have the same meaning of
the other variables.
The full path is:

These seem to be a good solution for monitoring high speed links.

But they are SNMPv2 objects !
We have tried to use MRTG to get these variables but we've got a No such

Name response. Using HP OpenView we can get the values of the two
variables and we have verified they have a good behavior.
We have currently installed MRTG ver. 2.5.2 that has a SNMPv1 module.

Can last MRTG version (2.8.8)  handle  SNMPv2 objects ?
Or there is a work around to make MRTG read 64 bit counters ?

Thanks for your attention

Giuseppe Larosa &
                            Simone Toniolo

CSELT S.p.A. Telecom Italia Group

Services and Applications
Via G. Reiss Romoli 274   -  10148  TORINO   Italy
Tel.  +39 011 228.70.44                           Fax. +39 011 228.50.69


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