Patent ID: 7313596
Filing Date: 2007-12-25
Classification: H04L

Abstract:
1. A multicast data communication system comprising: a transmitter that multicasts data using only unicast communication to a plurality of receivers via one or more repeaters provided on a unicast delivery path, each of the one or more repeaters, the transmitter, and the plurality of receivers being a node, each of the plurality of receivers comprising: a unit for transmitting a request message with the transmitter as a 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 of the data based on whether a receive interval of the request message is shorter than a predetermined time interval; and a unit which transmits the data toward the plurality of receivers when the node adjacent to the receiver side is determined to continue 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 when after the request message has been received from the node adjacent to the receiver side, the data or a delivery-table-creation packet has been received from a node adjacent to a transmitter side, a unit which registers the node adjacent to the receiver side which transmitted a request message after the delivery table was created, in the delivery table; a unit which determines whether the node adjacent to the receiver is continuing to request receipt of the data based on whether a receive interval of the request message is shorter than a predetermined time interval; and a unit which, when the node adjacent to the receiver side is determined to continue request receipt of the data, transmits a request message with the transmitter as a 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 the one or more repeaters actively transmit every request message; the request message comprises path information which represents a path from one of the plurality of receivers to a repeater or the transmitter where the request message was received; the one of the plurality of receivers transmits the request message containing information identifying the one of the plurality of receivers as the path information; when a node in which no delivery table is created exists between a source of the request message and the transmitter, the transmitter creates a delivery-table-packet containing the path information in the request message and transmits the delivery-table-creation packet toward the one of the plurality of receivers in accordance with the path information; and each of the one or more repeaters further comprises a unit which determines whether a respective delivery table has been created, and in the case where the respective delivery table has been created, when a node in which no delivery table is created exists between the source of the request message and the one or more repeater, a respective repeater creates a delivery-table-creation packet containing the path information in the request message, and transmits the delivery-table-creation packet toward the one of the plurality of receivers in accordance with the path information; and in the case where the respective delivery table has not been created, the respective repeater creates new path information, in which information identifying the respective repeater is added to the path information in the request message sent from the node adjacent to the receiver side, and transmits a request message containing the new path information with the transmitter as destination, and when the delivery-table-creation packet has been sent from the node adjacent to the transmitter side, forwards the delivery-table-creation packet to the node adjacent to the receiver side in accordance with the path information in the delivery-table-creation and creates the respective delivery table.