Overlapping CIDRs: A Good Practice for Environment Isolation in AWS
I’ve been designing VPC architectures in AWS, conventional wisdom tells us to avoid overlapping CIDR blocks. Heck, every single company I’ve worked at has an infrastructure or network team beholden to this idea. The reasoning is straightforward: non-overlapping CIDRs allow you to connect VPCs via peering, Transit Gateway, or other networking constructs if needed later. But what if preventing that connection is exactly what you want? I have been given side eye for even suggesting this practice before, but hear me out. ...