If you need to retain connectivity within a subnet while migrating virtual machine (VM) instances from an on-premises VMware source, consider using hybrid subnets. For example, you can use hybrid subnets during a multi-stage migration in which some VMs or IP addresses from an on-premises subnet need to be reachable to VM instances that are already migrated to Compute Engine.
A hybrid subnet combines an on-premises subnet and a Virtual Private Cloud (VPC) subnet into a single logical subnet. You can migrate individual workloads and instances from the on-premises subnet to the VPC subnet over time, without needing to change IP addresses. After all the workloads and VMs have been migrated, you can decommission the on-premises subnet.