25GB link between C220-M5 Hyperflex server and Catalyst 9500

[Art Astafiev]

We are doing new Cisco HyperFlex deployment based on C220 M5 servers (UCSHXM5) which come with 4 port Cisco VIC 1457. Two ports on this NIC can work in 25Gb mode, so we decided to utilize this since this is new deployment. Well ... we learned that by default connection between Catalyst 9500 25G ports didn't come up. This was because this NIC on server side by default has FEC setup at cl91 which is not an option in Catalyst 9500 switch. So, we had to adjust server side FEC to cl74 to make it work. Just sharing experience. 

To do this you have to go CIMC > Networking > Adapter Card MLOM > External Ethernet Interfaces > Double click on port-x line > after double click you will see drop down menu options next to parameters > change Admin FEC mode to cl74

Good luck.   

[premier-center]

I know this is kinda old, but did you have to do anything else to get it up and running? Been experimenting with ours when we have downtime and am having the worst luck getting it to work. I've got both sides set to FEC CL74 and I get nada, I'm almost wondering if it doesn't support the 25gbps twinax cables... Switch seems to see the cable properly, but the server never seems to notice them.

Going to look at grabbing some supported optics off the chart and see if it makes a difference, but wanted to start here.