You _can_ do NAT. Set up a different libvirt network on each machine, like this; 10.128.80.65 will have a libvirt network 192.168.65.0/24 10.128.80.66 will have a libvirt network 192.168.66.0/24 Set up each of these networks as routed networks. Now set up routing/iptables rules on each host to send traffic to each other, and NAT into the internal routed network On 31/10/12 01:46, libvirt-users-request@redhat.**com&lt;libvirt-users-request(a)redhat.com&gt;wrote: > Message: 1 > Date: Tue, 30 Oct 2012 07:10:55 +0000 > From: ??&lt;zhang_zhang(a)live.com&gt; > To:<libvirt-users@redhat.com> > Subject: [libvirt-users] Can VMs on different machines communicate > with each other without IP? > Message-ID:<BLU172-**W4666B32A6C9C8E75734C67FC620@**phx.gbl> > Content-Type: text/plain; charset="gb2312" > > > 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! > you can custom your iptable rules to solve it,i've noticed that you've got