Patent ID: 7450580

Claim:
An application-layer multicast system for multicast content data from a sender to a plurality of receivers through an intermediate system on a unicast network based on a data request message of each of the receivers, wherein the intermediate system comprises: a routing controller controlling application-layer multicast routing based on the data request message at application layer; and a plurality of data copying devices, each of which is made of a dedicated hardware circuit, for copying content data received from upstream to deliver each of copies of the content data to downstream based on the application-layer multicast routing, wherein said plurality of data copying devices communicate with the routing controller within the same segment to manage the content data to be relayed by the intermediate system using a management identification that is a port number corresponding to the content data uniquely assigned to the content data within the segment, wherein the routing controller manages said plurality of data copying devices, wherein each of the data copying devices works at layer 4 or lower, said plurality of data copying devices include a first data copying device and at least one other data copying device forming a hierarchical relationship for directly processing the content data on the same layer while bypassing the routing controller.