FEX migration from 5K NXOS to 9K ACI

[brian.holmes]

I have two FEXs off a 5K NXOS switch I am migrating to ACI...from my reading there is nothing you have to do to unregister a FEX, but I seem to be running into a problem when try to stage my new ACI configurations.  Here are my steps:

power up the staging FEX

attach the empty staging FEX to 9K downlinks of FEX 104

dump the port/epg configs for FEX 104 into ACI

power off the staging FEX

attach an the same empty staging FEX to 9K downlinks of FEX 103

power up the staging FEX

dump the port/epg configs for FEX 103 into ACI

- after this point I was going to simply swing the uplinks from the real FEX's to their new 9K ports.

after powering up FEX the second time ( red line above), the FEX keeps rebooting itself over and over...seems like maybe this process has confused the 9K by re-using the same FEX/Serial#  on different FEX downlinks.

Has anyone seen this type of behavior before?  Do I need to connect a different FEX serial# in order to get the 9K to flush out some cache or something?  or is there a command to unregister a FEX?

[brian.holmes · Accepted solution]

In the APIC, the FEX serial # is cached under the parent 9K switch...so basically you cannot use a single FEX to pre-stage multiple FEXs on the same 9K.   But I was able to use 2 FEXs and 2 9Ks to pre-stage 4 FEXs by simply crossing the FEX's between each 9K.

which is a little better than having to drag out 1 for 1 FEXs just to pre-stage configurations.