Which technology is used for communication between VMs which are running in different sites ?

Question

It might be possible one VM is spawned up at one site and another VM is launched at the different sites but both the VMs belong to same service and same sub net such as 10.1.1.x and 10.1.1.y series IP. Now I want to know which protocol/technology can be used to enable fast communication between these two VMs as appear as both are in same site/hardware.

Answer 1

I am not sure but I think VxLAN is used for communication with two virtual machines which belong to one subnet.
To achieve this OVS maintains VxLAN information and it worked as over lay network. This is know an overlay network because it uses IP layer of under lay network.
When one VM with IP 192.168.10.x residing at one physical machine wants to talk to another VM of same network 192.168.10.x series which is residing in another physical machine use the VxLAN tunneling.

VM1 forms IP packet (MAC + IP + TCP/UDP + Data) and send packet to physical machine. Based on target VM IP address it has mapping of VNI (Vx LAN Network Identifier) and add the header and encapsulate the packet in under lay network IP packet.

Once target physical machine receives this packet based on the VNI it comes to know which VM it suppose to deliver the packet.
This is how VxLAN works. I tried my best to explain VxLAN concept though I am not expert in networking.