Abstract: A virtual network provider system supports a virtual network including virtual machines that are each assigned to an underlay address of an underlay addressing scheme. The virtual network provider system further includes multiple routing domains each defined to include a different subset of the virtual machines. Each of the routing domains is assigned to a range of overlay addresses of an overlay addressing scheme. For each routing domain, the assigned range of overlay addresses is allocated among the subset of the virtual machines in the routing domain. The system further includes a virtual network host configured to use addresses of the overlay addressing scheme to selectively route messages between endpoints on select pairs of the virtual machines assigned to a same routing domain of the plurality of routing domains.