How to change External TEP pool reserved address count?

[YanL]

We have a few fabrics (5.3(2b)) with 1 External TEP Pool created but with 0 Reserved Address Count. We would like to deploy new remote leafs and use IPs from the External TEP Pool for the Unicats IP address like we do for other fabrics but I cannot find a way to modify/increase the reserveAddressCount from 0.

GUI Post or Postman error: "Create-only and naming props cannot be modified after creation, class=fabricExtRoutablePodSubnet, prop=reserveAddressCount". I can change active/inactive but nothing else. even when inactive I cannot change the reserved address count.

We would prefer to do this without deleting the External TEP pool and recreating it since it will be impactful, some IPs are assigned to APICs routable IPs and other objects from that pool. That particular fabric is multisite but not multipod.

thank you

[AshSe]

Hello @YanL 

In Cisco ACI, the reserveAddressCount property for an External TEP Pool cannot be modified after the pool has been created. This is a limitation of the system, as the reserveAddressCount is a "create-only" property. Unfortunately, this means that you cannot directly modify the reserved address count for an existing External TEP Pool.

Here are your options to address this issue:

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Option 1: Create a New External TEP Pool

The most straightforward solution is to create a new External TEP Pool with the desired reserveAddressCount value. However, as you mentioned, this may not be ideal because the existing pool is already in use, and deleting/recreating it would be disruptive.

Steps:

1. Create a new External TEP Pool with the correct reserveAddressCount value.
2. Gradually migrate the objects (e.g., APIC routable IPs, other assignments) to the new pool.
3. Once all objects are migrated, decommission the old pool.

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Option 2: Use a Different Subnet for Remote Leaf Deployment

If you cannot modify the existing External TEP Pool and cannot create a new one, you can consider using a different subnet for the remote leaf deployment. This would involve creating a new External TEP Pool specifically for the remote leafs.

Steps:

1. Allocate a new subnet for the remote leafs.
2. Create a new External TEP Pool using this subnet with the desired reserveAddressCount.
3. Use this new pool for the remote leaf deployment.

Why Can't reserveAddressCount Be Modified?

The reserveAddressCount property is used to reserve a specific number of IP addresses within the External TEP Pool for specific purposes (e.g., APIC routable IPs, other system functions). Changing this value after the pool is in use could lead to conflicts or inconsistencies in the IP address assignments, which is why the system enforces this restriction.

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Recommendation

The safest and most reliable approach is to create a new External TEP Pool with the correct configuration and migrate to it gradually. While this may require some planning and effort, it avoids potential disruptions and ensures that your configuration remains supported and maintainable.

If you are unsure about the impact of these changes or need further guidance, consult Cisco TAC for assistance.

Hope This Helps!!!

AshSe

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