VPC Peering enables two VPCs to communicate privately over the AWS network, as if they were part of the same network.
- Non-overlapping CIDR blocks are required.
- Not transitive:
- If VPC A ↔ VPC B and VPC B ↔ VPC C, VPC A cannot communicate with VPC C unless a direct peering connection (A ↔ C) is created.
Routing Configuration
- After establishing the peering connection, update route tables in each VPC to direct traffic to the other VPC’s CIDR range.
- Without the proper route table entries, traffic will not flow even if the peering connection exists.
Good to Know
- Can be created across accounts and across regions.
- You can reference a security group in a peered VPC only if:
- The VPCs are in the same region.
- This works even if they belong to different accounts.