Google cloud offers networking and communication that can span various regions and networks within the cloud.
Let’s take an example of a project that contains five networks. All of these networks span multiple regions across the world.
The regions that the networks are created in are spread out across US-East, US-Central, US-West, and Europe.
Each network contains separate virtual machines: A, B, C, and D.
VMs A and B are in the same network, Network 1, they can communicate using their internal IP address even though they are in different regions. In this example – Machine A is in the US-East region and Machine B is in the Europe region.
Therefore, even though the virtual machines exist in different locations across the world, take advantage of Google’s global fiber network and are part of Network #1.
Therefore, Virtual Machines A & B appear as though they’re sitting in the same rack, when it comes to a network configuration protocol.
VMs C and D however are not in the same network. They are in Network #3 and Network #4 respectively.
By default these VM’s must communicate using their external IP addresses even though they are in the same region.