APIC M2 TO M4 Migration

[AttaQ]

Hi everyone,

We’re planning to migrate from Cisco APIC M2 to M4 hardware in a Multi-Pod environment. Our current setup includes a single-node APIC cluster running version 5.3, and I’d like to gather input from those who’ve handled similar upgrades.

Option I’m Considering:
Bring up the new M4 APIC and connect it to the existing M2 cluster by changing the cluster size 1st, then gracefully decommission the M2.

Key Questions:

1. APIC Version Compatibility:
   The M4 APIC ships with a newer firmware version than 6.x. Do I need to downgrade it to 5.3 before adding it to the cluster, or can I add it first and downgrade it after joining?

2. Single APIC Risk:
   Any concerns with expanding from a single-node APIC cluster during this migration—especially in a Multi-Pod setup?

3. Alternative Migration Methods:
   Are there other recommended approaches for replacing APIC M2 with M4 that would reduce risk or simplify the process, particularly in a production Multi-Pod environment?

[julian.bendix]

Hey!

I have to ask - by "Our current setup includes a single-node APIC", do you mean that you really have only one single APIC running?

That is extremely risky and absolutely not recommended for Fabrics running in production.
I have only ever seen that in the Lab!

First of all, read through this thoroughly -> https://www.cisco.com/c/en/us/td/docs/dcn/whitepapers/cisco-apic-cluster-migration-guide-531.html 

1) Yes they have to run the same version - Upgrade your M2 to 5.3 and re-image the M4s to 5.3 via CIMC KVM vMedia.

2) Never done or seen this in prod - sounds risky, but then again, running only one single APIC is already super risky.

3) I guess best case would have been expanding with additional M2 Nodes then migrating to M4 with the recommended process.

Never seen the process of expanding the cluster and migrating to new hardware at the very same time.
So I can only make guesses and tell you what I would attempt.

I would attempt:
1) Upgrading the M2 APIC to 5.3
2) Expanding the Cluster with 2x M4 Nodes
3) Replace the M2 with the last M4
4) Upgrade the fabric to 6.0(x) once done

Right now recommended is 6.0(9d) -> https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/recommended-release/b_Recommended_Cisco_ACI_Releases.html 

Do you have your ACI Hardware under Cisco support? If yes you definitely should raise a TAC Case asking for a standby engineer while you attempt this process, which should be in a big maintenance window altogether.
Let me know if you want to discuss more.

BR
Jules

[AttaQ]

Thanks for the reply, single APIC setup is in the LAB environment. i'll give a try in the LAB and will update here.

[julian.bendix]

And your prod environment where you have to make the replacment, are there 3 active APICs?

Because if there are, then you have no trouble and can just follow the guide I shared in my last comment.

If you would have only one active APIC in your prod, but also have the same in a Lab - just attempt the whole process in the Lab first