Patent ID: 7894439
Filing Date: 2011-02-22
Classification: H04L

Abstract:
1. A communication device, in a Multi Protocol Label Switch (MPLS) network including at least a first area and a second area each as a unit for setting aggregation of pieces of route information, said first area being notified of aggregate route information into which the pieces of route information of a plurality of routes within said second area are aggregated, and using a Label Distribution Protocol (LDP) for generating a Label Switched Path (LSP) by distributing labels corresponding to the pieces of route information, being located within said first area and receiving a label mapping message for generating the LSP spanning between said first area and said second area and using one of the plurality of routes within said second area, said communication device comprising: an aggregate route information storage unit stored with the aggregate route information into which the pieces of route information are aggregated; a route information storage unit stored with the aggregate route information and pieces of route information; a label storage unit stored with the labels corresponding to the aggregate route information and the pieces of route information stored in said route information storage unit; a determining unit determining, when receiving the label mapping message, whether a route information contained in the label mapping message is stored in said route information storage unit or not; and a label control unit accepting, if the route information is not stored in said route information storage unit and a route specified by the route information is a route specified by one of the pieces of route information aggregated into the aggregate route information stored in said aggregate route information storage unit, the label mapping message and executing a label distribution process, wherein the label distribution process includes storing the route information in said route information storage unit, allocating a label to the route information, storing the label in said label storage unit, and forwarding the label mapping message containing the route information to a neighboring communication device, said determining unit, when receiving a label withdraw message for deleting the LSP of the aggregate route information into which the pieces of route information are aggregated, determines whether or not the aggregate route information and the pieces of route information aggregated into the aggregate route information, which are contained in the label withdraw message, are stored in said route information storage unit, said label control unit, if the aggregate route information and the pieces of route information aggregated into the aggregate route information are stored in said route information storage unit, accepts the label withdraw message and executes a label delete process, and the label delete process includes deleting the aggregate route information and the pieces of route information aggregated into the aggregate route information from said route information storage unit, deleting the labels corresponding to the aggregate route information and the pieces of route information aggregated into the aggregate route information from said label storage unit, and forwarding the label withdraw message containing the aggregate route information to a neighboring communication device.