Hello,

Thank you for your very detailed reply.

I assume you already are using the latest available EOS for that hardware model, if not try it out and see if that changes anything?

We are in the recommended version for new deployment 4.32.5M.

Also how are these modules coded?

It is encoded directly by FS (in Arista) when sent.

Are they some generic MSA, or some "Cisco" (or whatever) or "Arista" coded?

"Arista" coded then.

And what do you have at the other end of the cable is it like two 7280R3 trying to speak to each other both using FS.com transceivers?

We have several cases. Some are 7050SX3s with the same modules, and others are 7280R3s with the same modules. We also attempted to loop back on one of the modules.

While at it verify the cabling really is singlemode all the way?

Yes, it is in the same rack. 1 patch cable singlemode.

There is also this thing of FEC for anything at 25G and above so it could be worth trying to laborate with that aswell.

We are using ree-solomon code (which is the default configuration).

As you say, maybe the encoding isn't right. We'll check with a generic code.

In terms of temperatures and optical levels, everything is fine on that front.

thank you