1. A system comprising a computer processor, a computer-readable hardware storage medium, and program code embodied with the computer-readable hardware storage medium for execution by the computer processor to implement a method comprising: at an overlay network manager for a domain: receiving a communication request from a first entity within the domain; and determining whether the communication request comprises a request to communicate with a physical network sharing address space with the first entity or with a second entity outside the domain; wherein the overlay network manager bypasses address translation services for the communication request in response to determining the communication request comprises a request to communicate with the physical network; and wherein the overlay network manager provides address translation services to facilitate domain boundary crossing for the communication request in response to determining the communication request comprises a request to communicate with the second entity.