ACI APIC lab replace apic controller

[Pauwl]

Hi,

We have a LAB running with 1 APIC controller (L3). We want to replace the controller with .a L4 controller.

Is it possible to change the cluster size to 3, add the new controller, wait for the replication and then decommision the L3 controller and revert to a size of 1? Is this technically possible?

Thanks.

Regards Paul

[AshSe]

Hello @Pauwl 

No, the scenario you described is not technically possible in Cisco ACI. The APIC cluster size and behavior have specific requirements and limitations that must be followed. If you plan to move to a production environment in the future, you will need to deploy a minimum of 3 APIC controllers to meet the requirements for redundancy and high availability.

Hope This Helps!!!

AshSe

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[Pauwl]

Hi,

That is too bad. I have no intention to move this setup to prod, we have a seperate configuration for that. I know that only a 3 controller setup is supported but I am looking for a way to create a temporary solution to replace the controller inline.

My goal is to replace te APIC controller in the LAB without having to reinstall everything. Is it possible to add a spare APIC in a cluster of 1 and replace the current controller that way? Or any other tips or tricks?

Paul.

[AshSe · Accepted solution]

Hey @Pauwl 

Thank you for clarifying your goal! While your setup is in a lab environment and not production, the Cisco ACI architecture still enforces certain rules and limitations, even in a single-controller setup. However, there are some creative ways to achieve your goal of replacing the APIC controller without reinstalling everything. Let me walk you through the possibilities.

Key Considerations:

1. Single-Controller Cluster:

   • In a single-controller setup, there is no cluster quorum to worry about, so you have more flexibility compared to a production 3-node cluster.
   • However, adding a second controller to a single-node cluster is not officially supported, as the system expects a minimum of 3 controllers for a cluster.

2. Replacing the Controller:

   • The goal is to replace the L3 controller with the L4 controller while preserving the fabric configuration and avoiding a full reinstall.

---

Possible Solution: Backup and Restore with the New Controller

This is the most straightforward and supported way to replace the controller in a lab environment.

Steps:

1. Take a Full Backup:

   • Log in to the existing L3 APIC controller.
   • Navigate to System > Admin > Import/Export and take a full configuration backup (snapshot).
   • Save the backup file to an external location.

2. Deploy the New L4 Controller:

   • Power down the L3 controller.
   • Deploy the new L4 controller (either physical or virtual, depending on your setup).
   • During the initial setup of the L4 controller, configure it with the same fabric ID, pod ID, and other settings as the original L3 controller.

3. Restore the Configuration:

   • Once the L4 controller is up and running, log in to it.
   • Navigate to System > Admin > Import/Export and restore the configuration backup you took from the L3 controller.
   • The fabric configuration will be restored, and the new L4 controller will take over the role of the original L3 controller.

4. Verify the Fabric:

   • Ensure that the fabric is operational and that all leaf and spine switches are properly registered with the new controller.

---

Alternative: Adding a Temporary Controller (Not Officially Supported)

If you want to attempt adding the L4 controller temporarily to the single-node cluster, you can try the following steps. Note that this is not officially supported and may not work as expected.

Steps:

1. Deploy the L4 Controller:

   • Deploy the new L4 controller and configure it with the same fabric ID and pod ID as the existing L3 controller.

2. Manually Add the L4 Controller:

   • Log in to the L3 controller and attempt to add the L4 controller to the fabric as a second APIC.
   • This step may not work because the system expects a minimum of 3 controllers for a cluster.

3. Decommission the L3 Controller:

   • If the L4 controller successfully joins the fabric, decommission the L3 controller.
   • The L4 controller will take over as the primary controller.

4. Revert to a Single-Controller Setup:

   • After decommissioning the L3 controller, the L4 controller will remain as the sole controller in the fabric.

Caveats:

• This approach is not officially supported and may lead to unexpected behavior.
• If the L4 controller cannot join the fabric, you will need to fall back to the backup-and-restore method.

---

Final Recommendation:

The backup-and-restore method is the safest and most reliable way to replace the APIC controller in your lab environment. While it may seem like a bit of extra work, it ensures that your fabric configuration is preserved and avoids any unsupported operations that could lead to issues.

If you have any further questions or need clarification, feel free to ask!

Hope This Helps!!!

AshSe

Forum Tips: 

1. Insert photos/images inline - don't attach.
2. Always mark helpful and correct answers, it helps others find what they need.
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[Pauwl]

Thank you. I will try these suggestions.