Systems and methods are disclosed for configuring a communications network. In disclosed embodiments, for a communication network comprising fiber optic cables connected by switches and transceiver-transponders, a graph representing the communication network can be obtained with edges representing the fiber optic cables, and nodes representing the switches and transceiver-transponders. A set of service links can be determined for a path in the communication network based on a set of demands for the path. Each service link can represent data transmission by one of the transceiver-transponders through one or more of the fiber optic cables connected by zero or more of the switches. Sets of service links can be iteratively selected for progressively longer initial segments of the path. When the initial segment comprises the path, the set of service links for the initial segment can be selected as the set of service links for the path.