VPC Peering

• A VPC peering connection is a networking connection between two VPCs that enables you to route traffic between them using private IPv4 addresses or IPv6 addresses.

• Instances in either VPC can communicate with each other as if they are within the same network.

• The VPCs can be in different regions and different accounts.

• To send private IPv4 traffic from your instance to an instance in a peer VPC, you must add a route to the route table that's associated with your subnet in which your instance resides.

  • The route points to the CIDR block of the peer VPC in the VPC peering connection, and specifies the VPC peering connection as the target.

Transitive peering

• Instead of using VPC peering, you can use an AWS Transit Gateway that acts as a network transit hub, to interconnect your VPCs and on-premises networks.

• You have a VPC peering connection between VPC A and VPC B, and between VPC A and VPC C.

• There is no VPC peering connection between VPC B and VPC C.

  • So, you cannot route packets directly from VPC B to VPC C through VPC A.