Systems and methods for testing network connections of a centrally-controlled network

A computer network testing process to determine whether, given a network node that is unreachable by communication attempts from a controller on a control-plane network, the network node is still functioning to forward data packets on a data-plane network, or if the network node is fully non-functional on both the control-plane network and data-plane network. In order to make this determination, the testing process identifies a network node that is still reachable by the controller on the control-plane network, identifies a route between the controller and unreachable node, passing through the reachable node, and constructs an encapsulated test packet that is sent along this route. In response to sending the encapsulated test packet, the controller may, upon receipt of a confirmation packet, determine that the unreachable node is still functional on the data-plane network, or if no confirmation packet is received, mark the unreachable node as fully non-functional.