[ixpmanager] SFLOW Under Reporting?

[André Grüneberg]

Hi Ian,

Are you by any chance using vlan translation or L2 sub-interfaces (with non
default VLAN IDs) on your Arista gear?
In these cases the sFlow packets contain the VLAN ID on the wire and will
not be matched into the right buckets. We "enhanced" the sflow collector
script with some hack to map the VLAN ID. [I may go into details]
As far as I can see, you also offer private VLANs. These may also account
for some discrepancy between peering VLAN and overall traffic.
Unfortunately the private VLAN sFlow statistics are not (correctly) exposed
in P2P.

Besides those common issues, it also took us some effort to validate that
all peers are being counted "correctly". We believe that our results (
https://www.bcix.de/ixp/statistics/vlan) are very close to reality.

André


On Thu, 22 Jun 2023 at 11:54, Ian Chilton via ixpmanager <ixpmanager at inex.ie>
wrote:

> Hi,
>
> We have had a report from a member that the P2P graphs in IXP Manager
> are under-reporting compared to their own stats and to the overall
> traffic reported by MRTG. In fact on further comparison with the RRD
> files this morning and it seems we are seeing approximately half of the
> traffic vs the stats at their side.
>
> Looking in to this, I see that the per-protocol graphs in IXP Manager
> are reporting about half of our total exchange traffic, vs MRTG.
>
> I'm interested if anyone else has encountered a similar issue?
>
> How close are your MRTG reported traffic levels and that of sflow? (and
> what switch vendor are you using?)
>
> We are running Arista [EOS] and have the sflow sample rate set to [1 in]
> 16384.
>
> Thanks,
>
> Ian
> _______________________________________________
> INEX IXP Manager mailing list
> ixpmanager at inex.ie
> Unsubscribe or change options here:
> https://www.inex.ie/mailman/listinfo/ixpmanager
>


-- 
André Grüneberg, Managing Director
andre.grueneberg at bcix.de
+49 30 2332195 42

BCIX Management GmbH
Albrechtstr. 110
12103 Berlin
Germany

Geschäftsführer/Managing Directors: Jens Lietzmann, André Grüneberg
Handelsregister: Amtsgericht Charlottenburg, HRB 143581 B
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.inex.ie/pipermail/ixpmanager/attachments/20230622/69ce4aa2/attachment.htm>