Our datacenter recently made a purchase order for several Catalyst 9300's with C9300-NM-2Y network modules, along with N9K-C93180YC-FX's to serve as spine switches. After deploying two 93180's (peer-linked in HA) and several 9300's with 10g SFP's, I started swapping the 10gig tranceivers for SFP-25G-SR-S's. At first the interfaces wouldn't come up. I already went through the series of hoops involved with discovering I needed to use FEC, and now the interfaces are up/up, but I'm experiencing connectivity issues.
Specifically I'm unable to SSH into some devices. We use that switch primarily for management, but regardless there seems to be no rhyme or reason to what devices I can get to or not. What's really strange is that I can still ping them.
I THINK I've traced the issue back to the uplink port-channel between the 9300 and the vpc nexus switches, mainly because when I shut one of the network module ports and force everything over one wire the issue goes away. Is FEC somehow incompatible with port-channel aggregates?
For the record I'm running 16.12.03a on the 9300's and 7.0(3)I7(8) on the two nexus peers. VPC consistency shows everything in the green.
