I'm not sure if this is how VPC EC2 private addresses are supposed to work.
I have two instances in VPC each are allowed to talk to each other (security group), and each instance has two network interfaces. One out of the Two instances have Elastic IP set up and working fine.
The instances can ping and communicate with each other using the private ip that does not have an elastic IP assigned. But when i try to connect/ping with the private IP that does have an elastic IP on it the request times out.
Instances are Ubuntu 12.04 x64