Abstract: A replication of a physical network is created in the cloud. The replicated network safely validates configuration changes for any hardware network device of the physical network and the physical network end state resulting from the changes without impacting the physical network steady state. The replicated network creates virtual machines on hardware resources provisioned from the cloud. The virtual machines emulate network device functionality and have the same addressing as the network devices. Nested overlay networks reproduce the direct connectivity that exists between different pairs of the network devices on the virtual machines. A first overlay network formed by a first Virtual Extensible Local Area Network (VXLAN) provides direct logical connections between the cloud machines on which the virtual machines execute.