Nexus 9000 (vPC peer is not reachable over cfs)
Just had the pleasure of configuring a new pair of nx9ks. Setup of vPC is more or less the same as on Nexus 5000 however I did run into an issue of keepalives working, but the peer link being down with this message.
vPC peer is not reachable over cfs
CFS is used to exchange configuration between peer switches and check for inconsistencies. There is the official doc.
If that doesn’t run, vPC peers won’t work. CFS can work over ethernet and/or over ip(v6). The thing is, when you enable feature vpc this also gets enabled by default (over ethernet) and should just work.
In my case it came down to miss-configured peer ports (port channels) where one was trunk and the other not.
Another issue I experienced was PC connection between the existing N5K and the new N9K. When enabled the ports started flapping up and down givin strange messages about flow control. I found the solution in the last comment of this thread.
As the comment said, both switches cannot use the same vpc domain id. I could just write vpc domain 2 and all other configuration would stay the same.
