Split a CIDR of existing Pool

Question

Considering a initial footprint with a single region and having a IPv6 range /48 available, the following IPAM pool hierarchy was implemented (START). 
Now with extension to multiple regions and not having more IP ranges available, i need to split the CIDR and share it across the new regions (TARGET)

Is this technically feasible? What abou the impact on the resources already consuming IPs from existing /48 pool in eu-central-1?

------------------------------------------------------------
Assuming the following structure for a multi-region IPAM pool hierarchy:

**Start**:

toplevelpool-IPv6                        (/48)            
│
├── subpool-eu-central-1        (/48)
│   └── Primary                          (/48)

**Target**

toplevelpool                                (/48)  
│
├── subpool-eu-central-1        (/50)  
│   └── Primary                          (/50)  
│
└── subpool-eu-west-3            (/50)  
|   └── Primary                           (/50)  
│
└── subpool-eu-south-1          (/50)  
    └── Primary                           (/50)

Thank you!
Cheers

Arshdeep Grover · Answer

Yes, splitting the /48 IPv6 CIDR across multiple regions is technically feasible, but there are some important considerations.

Currently, you have a single /48 range allocated to the subpool-eu-central-1. If you plan to split this CIDR into smaller subnets (like /50s) for use in additional regions, such as subpool-eu-west-3 and subpool-eu-south-1, you can de-allocate part of the /48 from subpool-eu-central-1. You would then allocate /50 CIDRs to the new subpools.

To implement this, You would de-allocate the /49 and /50 ranges from subpool-eu-central-1 and reassign them to the other regional subpools.

PS:
* The parent pool should have its locale set to “None”, as the locale cannot be changed once assigned. If your parent pool has the locale set to match the original child pool (e.g., subpool-eu-central-1), this process will not work. In that case, you’d have to deprovision the entire /48 range and start fresh.
* Resources already consuming IPs from the /48 pool in subpool-eu-central-1 could be impacted. Be cautious, as existing IP allocations may need to be re-evaluated or migrated if the CIDR range is resized.

Split a CIDR of existing Pool

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