[mrtg] Graph not plotting, once my traffic goes above 562mbps

Eric Brander mailinglists at rednarb.com
Sun Oct 16 14:17:05 CEST 2011

On Sun, Oct 16, 2011 at 1:35 AM, Krushang Shah <krushang.shah at gmail.com> wrote:
> Dear All,
> I have plotting graph for one of my router interface, and it was working
> very much fine.
> But from last 3days, when my traffic goes above 562 MBPS. Graph doesn't
> plot, and when traffic goes below 562 MBPS, graph starting to plot again.
> this is the first time that my traffic goes above this levels.
> Please help me for this problem.
> MRTG Version: 2.17.2
> Polling interval: 1 minute.
> Attaching the graph for reference.

I'm thinking counter wrap due to a 32-bit counter. A 32-bit counter
will wrap (reach the maximum and start over from 0) after the number
exceeds 2^32. MRTG can handle it if it happens only once, but in a
60-second cycle it will happen more often if the rate is high enough.
I think you're exceeding that rate and so the counter is resetting to
0 twice during each polling cycle.

If I'm right then the remedy is to use 64-bit counters when polling
interfaces faster that Fast Ethernet.

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