[mrtg] Re: Counter Rollovers

Makai József jozsef.makai at siemens.com
Tue Jan 14 10:11:49 MET 2003

Hi Jim,

1. mrtg handles the counter rollovers. If the new value of the counter is
less then the previous one, mrtg knows that there was a counter rollover and
according to this counts the result.
But you have to take it into consideration that mrtg can calculate only with
ONE rollover. If the port speed is too high, or the checking period is too
long you can get false results. If the device supports, use the 64 bit

2. Dropouts can occur when you do not get back the result of an SNMP query.
If the traffic is too high you can loose the snmp packets.

Hope this helps you a bit.


> How does mrtg handle counter rollovers - or does it?
> I notice that on a number of very busy interfaces (switch 
> ports) that I
> periodically get "dropouts", where the graph will go to zero. 
>  I'm wondering if
> these are evidence of the counters rolling over and starting 
> again from zero.
> Jim

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