Workaround to overlapping IP address range

Question

I have a partner who is providing their services in a VPC of /19 and their customer only provided them with a /24 range. They will need to peer their VPCs. Because of this, they have overlapping address range and will thus not be able to use Transit Gateway, Direct Connect Gateway, VPC Peering, etc. My ask here is has anyone worked with a customer with a similar issue and what is a good practice/design around this? (Other than reallocating the address space to fit). The partner is looking at using a NAT as a workaround for now but is looking for a better alternative.

Accepted Answer

Unfortunately there is no great answer in this case. They could use NAT but once you need traffic to be originated in two directions then you will be required to do NAT in both directions. This will ultimately not scale well and will provide operational challenges.

They could possibly use something like Privatelink. But that will only work for traffic flows in one direction.

The best possible recommendation is to have them create a new VPC with non overlapping CIDRs and then migrate their resources to the new VPC.

Answer

https://aws.amazon.com/blogs/networking-and-content-delivery/connecting-networks-with-overlapping-ip-ranges/
check this link

Workaround to overlapping IP address range

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