How can I bridge two "VM Network" on two different site ?

I got Two site with a cluster on each.

each site has his own IP addressing, but I would like to bridge the "VM Network" on the distant site to the local "VM Network" so I could start a VM replicat on the distant site and it will be visible on the local "VM Network" without IP address changes.

I have no dedicated switch between the two site, I use routers and telecom provided MPLS link with 30Mbits throughput.

I was thinking of an openvpn link with TAP drivers so I can bridge at ethernet layer, but there may exist better solutions.

thank for your directions.

Cheers from Tahiti.

D.