ACI startup - APIC is on older version than switches

[goranje]

Hello,

We have situation where we have new ACI equipment, 3 APICs, 2 Spines and 4 Leafs.

But currently before startup we have situation when:

APICs have pre-installed  version 4.0.

Spines are on 13.0

Leafs are on 14.2. and they are newest model (according ACI-mode Switches Hardware Support Matrix the hardware is not even supported in version 4.0 on APIC), the leafs are so new that they do not support any older version than 14.2)

What should be proper way of startup?

The question are:

Will APIC discovered Leafs with new version and hw not supported?

Will APIC discovered Spines with older version?

If APIC do not discover the LEAFs:

Should first do upgrade on APIC to version 4.2?

How it can be done on 3 APIC if Fabric is not initialized, and they are not in cluster?

What happens if one APIC is on version 14.2 (if we upgrade it after first boot up) and if switch discovery is OK, will other APICs that are on older version upgrade automatically when discovered and cluster formation?

Best regards,  

[Claudia de Luna]

Hi @goranje ,  This scenario is not uncommon.  First thing I do when I get my hands on ACI equipment is to console in and check to see what version everything has.

After that, I try to get everything on the same major version at least.  In your case I would upgrade everything to 4 (14) and in fact since you have some minimum requirements on your new leafs I would upgrade the spines to 14.2.

With your APICs running 4 I would bring everything up on 4 and then upgrade the entire fabric to 4.2/14.2 (just to make sure all the switch firmware (fpga/bios) gets upgraded as well).  Either leave all the APICs on 4 or upgrade them all to 4.2...don't do only one.

Your APICs will not "automatically" upgrade if one is running a higher version.  You will need to initiate the upgrade and as I mentioned, before doing anything else upgrade manually the fabric switches to the same version.

Technically everything should be on the same version and Cisco strongly recommends not running a fabric with disparate versions for any length of time.  I think if it were me I'd get all the APICs on the same version (4.2) before discovery just to be avoid anything unforeseen but I tend to be very conservative (as its usually a clients fabric :D).

Here is a good guide for you:

https://unofficialaciguide.com/2018/12/04/upgrading-aci-fabric-the-4-0-way/