VPC Peering Connection Usage Examples

A VPC peering connection is a networking connection between two VPCs in the same region and enables them to communicate. Table 1 lists different scenarios of using VPC peering connections.

**Table 1** VPC peering connection usage examples
Location	CIDR Block	Description	Example
VPCs in the same region	VPC CIDR blocks do not overlap. Subnet CIDR blocks of VPCs do not overlap.	You can create VPC peering connections to connect entire CIDR blocks of VPCs. Then, all resources in the VPCs can communicate with each other.	Using a VPC Peering Connection to Connect Two VPCs
VPCs in the same region	VPC CIDR blocks overlap. Some subnet CIDR blocks overlap.	You can create VPC peering connections to connect specific subnets or ECSs from different VPCs. To connect specific subnets from two VPCs, the subnet CIDR blocks cannot overlap. To connect specific ECSs from two VPCs, each ECS must have a unique private IP address.	Using a VPC Peering Connection to Connect Subnets in Two VPCs
VPCs in the same region	VPC CIDR blocks overlap. Some subnet CIDR blocks overlap.		Using a VPC Peering Connection to Connect ECSs in Two VPCs
VPCs in the same region	VPC CIDR blocks overlap. All subnet CIDR blocks overlap.	VPC peering connections are not usable.	Unsupported VPC Peering Configurations

Alternatively, you can use enterprise routers to connect VPCs in the same region. Enterprise Router is more suitable for complex networking that needs to connect multiple VPCs. With enterprise routers, you do not have to create a large number of VPC peering connections or add too many routes. This makes your network topology simpler and more scalable.

All route tables in a VPC can have a maximum of 1,000 routes. If you want to create VPC peering connections to connect multiple VPCs, consider this restriction when planning the networking.

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