To create a VPC peering connection with another VPC, you need to be aware of the followinglimitations and rules: You cannot create a VPC peering connection between VPCs that have matching or overlapping CIDRblocks. You cannot create a VPC peering connection between VPCs in different regions. You have a limit onthe number active and pending VPC peering connections that you can have per VPC. VPC peeringdoes not support transitive peering relationships; in a VPC peering connection, your VPC will nothave access to any other VPCs that the peer VPC may be peered with. This includes VPC peeringconnections that are established entirely within your own AWS account. You cannot have more thanone VPC peering connection between the same two VPCs at the same time. The MaximumTransmission Unit (MTU) across a VPC peering connection is 1500 bytes. A placement group can spanpeered VPCs; however, you will not get full-bisection bandwidth between instances in peered VPCs.Unicast reverse path forwarding in VPC peering connections is not supported. You cannot reference asecurity group from the peer VPC as a source or destination for ingress or egress rules in yoursecurity group. Instead, reference CIDR blocks of the peer VPC as the source or destination of yoursecurity group's ingress or egress rules. Private DNS values cannot be resolved between instances in peered VPCs. Reference: http://docs.aws.amazon.com/AmazonVPC/latest/PeeringGuide/vpcpeering-overview.html#vpcpeering-limitations