CIDR blocks overlap
You can not create a VPC peer between VPC has matched or overlapping IPv4 CIDR block connection.
If there are multiple VPC IPv4 CIDR blocks, if any of the CIDR blocks overlap, you can not create a VPC peer connection (regardless of whether you intend only VPC peer connection for communicating between non-overlapping CIDR block).
This limitation also applies to non-overlapping VPC IPv6 CIDR block. Even if you only intend to VPC peer connection for IPv6 traffic, if VPC has matched or overlapping IPv4 CIDR blocks, you can not create a VPC peer connections.
VPC regional peer connection does not support IPv6-communication.
Edges through a gateway connected to the edge router or private
If any of the peer relationship in a VPC have one of the following connections, you can not expand a peer relationship to the connection:
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VPN connection or connection to the corporate network between AWS Direct Connect
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Establish an Internet connection through an Internet gateway
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Established through a NAT device in a private subnet Internet Connection
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AWS VPC terminal nodes and services; e.g., Amazon S3 terminal node.
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(IPv6) ClassicLink connection. You may be connected between the other side of the VPC instances enable IPv4 communication with the EC2-Classic examples VPC peer link. However, EC2-Classic does not support IPv6, so you can not extend this connection for IPv6 traffic.
VPC can not use the B terminal is connected to the VPC VPC node A direct access Amazon S3.
Traffic from the Internet can not be used connected to the Internet gateway VPC A direct access VPC B.
Traffic from the corporate network can not be connected using a VPN connection or AWS Direct VPC A Connect to directly access the VPC B.
