Patent ID: 8089905

Claim:
A multicast distribution system in which multicast distribution is performed from a distribution source router to a plurality of distribution destination routers constituting a multicast network formed on a mesh virtual network, wherein the distribution source router comprises: a monitor unit configured to monitor and detect a CPU load ratio in the distribution source router, a communication characteristic of a multicast group constructed on the multicast network, and a path characteristic of the mesh virtual network; a storage unit configured to store a threshold value of the CPU load ratio and a threshold value of the communication characteristic of the multicast group; and a control unit configured, based on the path characteristic of the mesh virtual network detected by said monitor unit and at least one of a result of comparison between the CPU load ratio detected by said monitor unit and the threshold value of the CPU load ratio stored in said storage unit and a result of comparison between the communication characteristic of the multicast group detected by said monitor unit and the threshold value of the communication characteristic of the multicast group stored in said storage unit, to start reconstruction of a multicast tree that defines a packet distribution path from the distribution source router, and based on the multicast tree, start recreation of a routing table that decides a multicast distribution path, wherein said control unit of the distribution source router is configured, in a case where at least one of values of the CPU load ratio monitored by said monitor unit and the communication characteristic of the multicast group monitored by said monitor unit exceeds the threshold value thereof, to reduce a number of branches and increase a depth of the multicast tree and start reconstruction of the multicast tree based on the reduced number of branches and the increased depth of the multicast tree, and a virtual path selected, from among a plurality of virtual paths, so as to have a path characteristic margin.