What Is a VPC Peering Connection?
A VPC peering connection connects two VPCs to enable them to communicate using private IP addresses. The VPCs to be peered can be under the same account or different accounts, but must be in the same region.
Figure 1 shows an application scenario of VPC peering connections. Figure 1 Two VPCs connected by a VPC peering connection
VPC Peering Connection Creation Process
A VPC peering connection can only connect VPCs in the same region.
- If two VPCs are in the same account, the process of creating a VPC peering connection is shown in Figure 2.
For details about how to create a VPC peering connection, see Creating a VPC Peering Connection to Connect Two VPCs in the Same Account.
Figure 2 Process of creating a VPC peering connection between VPCs in the same account
- If two VPCs are in different accounts, the process of creating a VPC peering connection is shown in Figure 3.
For details about how to create a VPC peering connection, see Creating a VPC Peering Connection to Connect Two VPCs in Different Accounts.
If account A initiates a request to create a VPC peering connection with a VPC in account B, the VPC peering connection takes effect only after account B accepts the request.
Figure 3 Process of creating a VPC peering connection between VPCs in different accounts
Notes and Constraints
- A VPC peering connection can only connect VPCs in the same region.
- If the local and peer VPCs have overlapping CIDR blocks, the VPC peering connection may not take effect. For example, if the CIDR block of a VPC is 192.168.0.0/16 and that of another VPC is 192.168.0.0/16 or 192.168.0.0/18, the CIDR blocks overlap.
- By default, if VPC B is peered with VPC A that has EIPs, VPC B cannot use EIPs of VPC A to access the Internet.
To enable this, you can use a NAT gateway or configure an SNAT server to allow the ECSs in VPC B to access the Internet through the EIPs of ECSs in VPC A.