US Patent 9686176 Constrained and viable path computation systems and methods

Path calculation systems and methods for determining a path, based on constraints and rules, for a connection at one or more layers in a network, include determining a path exploration map of the network based on a multi-layer network model of the network defining external edges and intra-node paths, the path exploration map comprising every external port in the network that is reachable from a source port; and utilizing the path exploration map to determine a viable path, from a destination port to the source port, subject to the constraints and the rules and based on a cost.