Graphing Peering

Daniel Golding dgolding at
Thu Jan 20 15:59:06 UTC 2005


The 32 bit counters are a significant problem when using gigabit ethernet
public peering interfaces. Needless to say, MAC accounting was not designed
for gigabit speeds. Frequent polling is, sadly the only solution. If you
write your own scripts, make sure to account for counter wrapping.

- Dan

on 1/20/05 9:45 AM, "druid at" <druid at> wrote:

> On Wed, 2005-01-19 at 22:41, andrew matthews wrote:
>> Anyone have any suggestions on graphing peering on a cisco router? I'm
>> using mrtg and i did mac address accounting but the numbers are off.
> off in what sense? We use mac-accounting, snmp nad mrtg to graph per
> peer utilization. The following script is helpful
> I reworked it to spit out the AS number instead of the ip address. The
> issue you then have is that multiple sessions with one As number all
> show as the same target. Which MRTG does not like. You can fix that as
> well of course in the script. And it does not "autoscan", which means
> that if people change their mac-address, you lose the data, until you
> rerun the script.
> Another problem you might run into is counter wrapping. When polling
> every 5 minutes, some counters may wrap. (there is no 64 bit counter for
> the mac-address accounting). So you have to run it in short timeframes,
> causing more cpu utilization.
> But all in all, mac-accounting and Netflow source-as give you a very
> good overview of your network flows.
> Frank 

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