VPC peering connects VPCs so resources communicate via private IPs. Traffic stays on the provider's network.
Creating peering:
Request peering from VPC-A to VPC-B
Accept the request in VPC-B
Add routes in both VPCs
Update security groups
Limitations:
- No transitive routing (A-B and B-C does not mean A reaches C)
- CIDRs cannot overlap
- One peering per VPC pair
Use cases:
- Shared services VPC
- Separating production/development
Peering works for small numbers of VPCs. Beyond -, consider Transit Gateway.