Good to hear, we had this happen in the past then the link went down. I would try and flap the port and reboot etc and see if it keeps working for you. We had it in production where something didn't come back up and was not fun trying to fix it.SUCCESS!! Kinda...
So I got to thinking about the cables I am using and the post I linked above and wondered what could be the problem. The DACs I have are 10GTek branded and "Cisco Compatible". I got to digging into just what that cable is reporting to the switch/SIOC and found out that it is NOT encoded correctly. It is being reported as: OEM QSFP-H40G-CU3M. When it supposed to say CISCO QSFP-H40G-CU3M.
In my endless empire of dirt, i was able to source a genuine OEM bonafide Cisco QSFP+ to 4x SFP+ cable. Splitting 40G into 4x10G. I have an old PoE switch with some SFP+ ports, figured what the heck, lets try it.
Link came up immediately, 4x10G happy as can be...
Annoyed, I put my Arista optic back in the SIOC, 1M OM3 cable and Arista optic at the other end. Link came up.
WTF????
Long story short, you can "fool" the SIOC into accepting any optic as long as it sees an OEM one first. The link is solid and working fine, as long as it doesn't flap. Not ideal, but it lets me move forward. OEM Optics are on the way, we're back on track.
Glad to hear however we have some 40g to 4x10g cisco breakouts and a lot of other things. Sadly these are for a large project for a few months from now. Hopefully we will get to play with them more ahead of time.
I believe we have 20 of these systems I believe at the moment.