You need UDP working between them. the fact that you have KVM probably indicates that you need to do some config to make UDP work between them.
Thanks for your response.
I am also evaluating MRG/qpid in clustered mode and it works perfectly.
This is done using multicast ip address and port.
I can send messages from serverA and receive them on serverB using MRG/qpid.
Does that suggest that UDP is working between these servers?
I am using the same ip address and port to cluster HornetQ.
You are using a wrong (invalid UDP address).
I suggest you use the default one.
You are most certainly using a different UDP IP on MRG/qpid.