Patent ID: 7986641

Claim:
A multicast data communication system which multicasts data using only unicast communication via one or more repeaters provided on a unicast delivery path from a transmitter to a plurality of receivers, each of the one or more repeaters, the transmitter, and the plurality of receivers being a node, the transmitter being a root of a multicast tree of delivery paths from the transmitter to the plurality of receivers, each of the plurality of receivers comprising a unit for transmitting a reception request message for requesting receipt of multicast data with the transmitter as the destination at a time interval which is shorter than a predetermined value, the transmitter comprising: a unit which determines whether a node adjacent to a receiver side is continuing to request receipt of the data, based on whether a receive interval of the reception request message is shorter than a predetermined time interval; and a unit which transmits the data toward the plurality of receivers when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, and each of the one or more repeaters comprising: a unit which creates a delivery table for registering one or more nodes adjacent to the receiver side where the data should be delivered to only a) after the reception request message has been received from the node adjacent to the receiver side and b) when the multicast data or a delivery-table-creation packet is received from a node adjacent to a transmitter side; a unit which registers the node adjacent to the receiver side which transmitted a reception request message after the delivery table was created, in the delivery table; a unit which determines whether the node adjacent to the receiver side is continuing to request receipt of the data, based on whether a receive interval of the reception request messages is shorter than a predetermined time interval; and a unit which, when it has been determined that the node adjacent to the receiver side is continuing to request receipt of the data, transmits a reception request message with the transmitter as the destination at a time interval which is shorter than a predetermined value, and in addition, replicates the data, sent from the node adjacent to the transmitter side, and delivers replicated data to the node adjacent to the receiver side, which is registered in the delivery table, wherein each of the plurality of receivers and one or more repeaters spontaneously transmit every reception request message.