MULTICAST DISTRIBUTION METHOD, DISTRIBUTION DEVICE AND DISTRIBUTION PROGRAM

PROBLEM TO BE SOLVED: To provide a multicast distribution method in which the band of a communication channel for use in multicast distribution of a video stream, or the like, can be used efficiently, and to provide a distribution device and a distribution program.SOLUTION: In a group consisting of a plurality of interlinked lower routers 3 connected with an upper router 1 repeating/distributing the streams of a plurality of channels separately by different communication channels 52, the lower routers 3 each report the individual channels which started or stopped reception from the upper router 1 to other devices in the group to which the lower routers 3 belong, thus grasping a channel group through which each device is receiving from the upper router 1. If a channel has been received already by another device when distribution of the arbitrary channel is requested from a user terminal 4 under control, the stream of that channel is received from the other device by link connection and distributed to the user terminal 4 of request source.