Patent ID: 8320255

Claim:
A method for computing a traffic engineering (TE) label switched path (LSP) that spans multiple domains of a computer network from a head-end node of a local domain, through one or more intervening remote domains, to a tail-end node of a destination domain, the method comprising: requesting path segments from a path computation element (PCE) in each of the one or more intervening remote domains and in the destination domain, the path segments representing a first plurality of possible paths within each respective intervening remote domain between every entry border router within that domain that is in communication with an upstream domain and every exit border router within that domain that is in communication with a downstream domain and representing a second plurality of possible paths within the destination domain between every entry border router of the destination domain in communication with an upstream domain and the tail-end node; receiving, at the head-end node, the path segments from the PCEs; calculating a local topology that includes a third plurality of possible paths within the local domain; combining the received path segments that represent the first plurality of possible paths within each respective intervening remote domain between every entry border router within that domain that is in communication with an upstream domain and every exit border router within that domain that is in communication with a downstream domain, with the received path segments that represent the second plurality of possible paths within the destination domain between every entry border router of the destination domain in communication with an upstream domain and the tail-end node, and with the third plurality of possible paths within the local domain, to create an overall topology that includes all possible paths within the local domain, the one or more intervening remote domains, and the destination domain; and performing a path computation, at the head-end node, to find the best path extending from the head-end node to the tail-end node based on the overall topology.