[libvirt-users] Can VMs on different machines communicate with each other without IP?

Dear all, I confront a somehow strange situation: I have two machines configured with ip 10.128.80.65 and 10.128.80.66 respectively. Each has several VMs running on it. The problem is that I have no more ip ( such as 10.128.80.67...) to allocate to VMs, but VMs need to communicate with each other even when they are on different machines. Two network options exist: NAT and bridge. 1) NAT But VMs on different machine cannot communicate with each other. 2)bridge But there is no more ip for vm to be bridged to host machine. Is there any other way to work around this problem? many thanks!