[mrtg] Re: Inaccurate Peaks

[Steve Shipway]

> On a under utilized STM-64 link, we observe many instances of 
> inaccurate peaks in the graph. These peaks appear only on the 
> IN-Traffic. When compared with the OUT traffic on the other 
> end, except for the peaks the other points seem to match well.
> We analysed the incoming SNMP packets using ethereal and did 
> not see such large values. Has anyone observed such a 
> behaviour before ? Also, are there any known issues like this 
> that someone is aware of ? Thanks for the help.

Could be due to counter resets, and MRTG incorrectly assuming a counter
wrap.  I'd suggest you use the AbsMax[] directive to force it to ignore
values you know are way too high.  Also, check to see if the SNMP agent has
been reset at corresponding times, or an interface reset, or something
similar which could have caused the SNMP counter for that interface to reset
to zero and confuse MRTG.

Steve


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