Patent ID: 8565218

Claim:
A computer implemented method of route discovery for an end-to-end path in a network for a flow, wherein a path is attempted to be discovered that satisfies QoS constraints for multiple metrics for the flow, the method comprising: receiving, by a computer system coupled to the network, a path request for the flow, wherein the path request identifies the QoS constraints for the flow; determining, by a processor in the computer system, whether the path request is infeasible or undecideable, wherein the path request is undecideable if a determination is made that a feasible path does not exist based on information from a local QoS table and a determination is made that the path request is not infeasible, and if the QoS constraints for the path request fall in an undecideable region of metrics for the QoS constraints, the undecideable region being an area outside of areas for any feasible paths and an area for an infeasible region; determining if the path request is infeasible and if determined to be infeasible denying the path request; and determining if the path request is undecideable and if determined to be undecideable sending route discovery messages only to neighbors that previously sent an advertisement for a destination for the flow to determine whether to admit or reject the path request, wherein to determine whether to admit or reject the path request includes aggregating advertisements for the destination with local link metrics to determine best paths to the destination until a path is found that satisfies the QoS constraints or a determination is made that a path does not exist that satisfies the QoS constraints.