[rescue] What is this traffic?

Mauricio Tavares raubvogel at gmail.com
Thu Oct 29 13:16:45 CDT 2015

On Thu, Oct 29, 2015 at 12:34 PM, Mike Spooner
<mike.spooner.ux at gmail.com> wrote:
> Sorry to be late to this thread... from the description of observed
> behaviour, this sounds very much like the switch and router have a
> disagreement about Ethernet "duplex" mode - during negotiation, one has
> picked half-duplex, the other full-duplex, causing a stream of "late
> collision" errors on the one using half-duplex mode.
> In this situation, I have seen effective throughput drop to 10% of what
> should be possible, due to all the errors and semi-synchronised
> transmission-backoffs.
> If you have access to any kind of "configuration settings" interface on the
> router, and that provides a way to change the Ethernet duplex setting on
> the "inside" interface, it may well be worth changing that, but be careful
> to not cut yourself off if it does not work (ie: use a modern PC directly
> conencted to apply the change; don't use a 20+ year-old Sun workstation).
> If this resolves the storm, half-duplex-all-over isn't ideal, but should
> give you between 50% and 80% of the theoretical throughput (depends a bit
> on the exact traffic pattern).
      I was going to suggest to use a reasonably modern machine with
some kind of windows connected directly to the router and run
wireshark since it gives a nice graphical view of the amount of junk
flying on the wire.

And then put the laptop between switch and router and probulate the traffic.

> Regards,
> Mike
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