Problem establishing 25G link between Nexus 93180YC-FX3 and Cat 9300

[stevesmith741]

Anyone out there been able to get this particular combination working?

Nexus N9K-C93180YC-FX3 - SFP-H25G-CU3M - Catalyst C9300-48P (C9300-NM2Y)

A few posts suggest success with paring a Nx93180 with a Catalyst, but sometimes the SFP used is different or the Catalyst involved is a 9500, and for whatever reason the settings suggested in these posts aren't working for us.

We've tried hard-coding FEC at both ends, hard-coding one end and auto on the other, auto speed setting one end and fixed at the other, fixed at both ends, auto at both, you name it. Speed settings on the Nexus end were manipulated by configuring the port-channel. There are a huge number of combinations possible so we'd prefer to avoid having to try every one of them. Hopefully someone has the magic prescription!

Thanks in advance,

Steve

[f00z]

What code versions are you running?  3m cable requires FEC on host port, 2m doesn't. 3m FEC has to be BASE-R (FC-FEC) (i think this is CL74 on the 9300 side and FC-FEC on nexus, 9300 network modules are weird, don't seem to auto negotiate anything)

[stevesmith741]

Thanks f00z. We've managed to get it working. Appears there is a bug (not public) and a workaround. I'll post the exact solution when I get the details.

[cctv-network]

I have the same problem: Connecting Nexus 93180YC-FX to C9500-48Y4C using SFP-H25G-CU5M cables.

The links do not go UP.

Did you managed to find a solution?

[cctv-network]

No need for an answer anymore, we figured out the solution.

For whoever has the same problem:

On Nexus:

interface Ethernet1/xx
  fec fc-fec

On Catalyst

interface TwentyFiveGigE1/0/xx
  speed nonegotiate
  fec cl74

And after these commands, the interfaces came up.

[David Block]

DUDE!   Thank you so much for posting this.   I have been searching for quite a while on why my SFP-10/25G-csr's between a Cat 9300 and Nexus 91380yc-fx werent coming up.

mine are in a port channel and the speed nonegotiate wouldnt take on the Cat switch, but the fec cl74 on the CAT and fec off on the nexus side did the trick!