Arista Switches rebooting

Tue May 5 06:09:01 UTC 2020

On Mon, 4 May 2020 at 23:06, Ethan O'Toole <telmnstr at 757.org> wrote:

> We found a bug on the 64 port x 100gig model that if you insert a quad
> twinax 10gig fanout cable in many of the ports it will trigger a reboot.I

I've seen a similar issue in another vendor, where specific SFP
inserted would reload the linecard. This was because the SFP didn't
answer fast enough to I2C queries and the polling code couldn't handle
the error so it crashed the whole linecard. Vendor didn't fix the
code, because it didn't happen on vendor optic, while obviously they
must have understood they can't guarantee vendor optic answers in a
timely manner in I2C.

I2C is a pretty terrible bus, particularly if you try to actually hang
everything off of a single I2C bus, single misbehaving speaker and you
might get your power supplies offline. Hopefully we'll move to I3C or
10SPE Ethernet soon. Or maybe some sort of I2C switch where every
connection is on its own bus.

-- 
  ++ytti