It appears that the only way to get two Amazon EC2 nodes in different regions to see each other is through their associated external elastic IPs. However, JGroups only provides support for external IPs in the TCP protocol. FD_SOCK and STREAMING_STATE_TRANSFER do not provide this. Since Infinispan depends on STREAMING_STATE_TRANSFER, it currently does not seem possible to have Infinispan instances in different EC2 regions communicating with each other through the JGroups layer. Request to add external-ip support to all protocols that make P2P connections (or any other way to do this, so long as the end result is the ability for Infinispan/JGroups instances to talk to each other in this scenario).