common method to count traffic volume on IX

Patrick W. Gilmore patrick at
Tue Sep 17 18:15:14 UTC 2013

On Sep 17, 2013, at 12:11 , Martin T <m4rtntns at> wrote:

> Thanks for all the replies!
> Nick,
> counting traffic on inter-switch links is kind of cheating, isn't it?
> I mean if "input bytes" and "output bytes" on all the ports facing the
> IX members are already counted, then counting traffic on links between
> the switches in fabric will count some of the traffic multiple times.
> Patrick,
> how does smaller sampling period help to show more traffic volume on
> switch fabric? Or do you mean that in case of shorter sampling periods
> the traffic peaks are not averaged out and thus peak in and peak out
> traffic levels remain higher?

The graph has a bigger peak, and DE-CIX has claimed "see, we are bigger" using such graphs. Not only did they not caveat the fact they were using a non-standard sampling method, they have refused to change when confronted or even say what their traffic would be with a 300 second timer.


> On 9/17/13, Nick Hilliard <nick at> wrote:
>> On 17/09/2013 14:43, Patrick W. Gilmore wrote:
>>> And yes, DE-CIX is more than well aware everyone thinks this is .. uh ..
>>> let's just call it "silly" for now, although most would use far more
>>> disparaging words. Which is probably why no serious IXP does it.
>> It's not silly - it's just not what everyone else does, so it's not
>> possible to directly compare stats with other ixps.  I'm all in favour of
>> using short (but technically sensible) sampling intervals for internal
>> monitoring, but there are good reasons to use 300s / ingress sum for
>> prettypics intended for public consumption.
>> Nick

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