MULTICAST INFORMATION DISTRIBUTION CONTROL METHOD AND SYSTEM, AND SERVER AND CLIENT

PROBLEM TO BE SOLVED: To provide a multicast information distribution control method and system that can provide an opportunity of selecting reception of other multicast information by a client receiving multicast information by an external device. SOLUTION: The task above can be attained by the multicast information distribution control method and system that allows an information distribution server to identify a client receiving 1st multicast information, allows other communication unit than the client via a prescribed communication network to transmit request information to the identified client, allows the client to conduct the leave processing to terminate the reception of the 1st multicast information on the basis of the received request information, and to conduct the join processing to attain reception of 2nd multicast information from the information distribution server.