VPC peering connections created between VPCs that have overlapping subnet CIDR blocks may not take effect.
You cannot have more than one VPC peering connection between the same two VPCs at the same time.
You cannot create a VPC peering connection between VPCs in different regions.
You cannot use the EIPs in a VPC of a VPC peering connection to access resources in the other VPC. For example, VPC A is peered with VPC B, VPC B has EIPs that can be used to access the Internet, you cannot use EIPs in VPC B to access the Internet from VPC A.
To request a VPC peering connection with a VPC of another tenant, the peer tenant must accept the request to activate the connection. If you request a VPC peering connection with a VPC of your own, the system automatically accepts the request to activate the connection.
After a VPC peering connection is established, the local and peer tenants must add routes in the local and peer VPCs to enable communication between the two VPCs.
VPC A is peered with both VPC B and VPC C. If VPC B and VPC C have overlapping CIDR blocks, routes with the same destinations cannot be added in VPC A.
To ensure security, do not accept VPC peering connections from unknown tenants.
Either owner of a VPC in a peering connection can delete the VPC peering connection at any time. If a VPC peering connection is deleted by one of its owners, all information about this connection will be automatically deleted immediately, including routes added for the VPC peering connection.
Currently, the route table of a VPC takes effect for all subnets in the VPC. You cannot add a route table dedicated for a specific subnet. The route preference is as follows: direct route > VPC peering connection route > custom route.
If two VPCs in a VPC peering connection have overlapping CIDR blocks, the peering connection can only enable communication between two subnets in the two VPCs. If subnets in the two VPCs in a VPC peering connection have overlapping CIDR blocks, the peering connection does not take effect. To create a VPC peering connection, ensure that the two VPCs involved do not contain overlapping subnets.
You cannot delete a VPC for which VPC peering connection routes have been configured.