Patent ID: 7876675
Filing Date: 2011-01-25
Classification: H04L,H04N

Abstract:
1. A multicast network system, in which each packet sent out from a source device is copied and transmitted to a plurality of user terminals, the multicast network system comprising: a multicast network including a plurality of relay nodes hierarchically provided, each of which copies an input packet and outputs the copied packet to a next relay node; a monitoring server coupled to a relay node located at a highest end of the hierarchy; and a plurality of user terminals, which are respectively coupled to corresponding relay nodes, each of which is located at lowest ends of the hierarchy, wherein the monitoring server comprises: an acknowledgment request message generating unit to generate an acknowledgment request message which includes an acknowledgment probability and to send the generated acknowledgment request message to the plurality of user terminals through the multicast network; a collecting unit to collect acknowledgment messages, which are sent from the user terminals to respond to the acknowledgement request message; and a collection number comparing unit to compare the number of the acknowledgment messages collected by the collecting unit with an expected number of acknowledgment messages calculated from the acknowledgment probability and the total number of the user terminals, each of the plurality of user terminals comprises: a random number generating unit to generate a random number; and an acknowledgment message sending unit to determine whether an acknowledgment is needed for responding to the acknowledgment request message based on a comparison of the acknowledgment probability included in the acknowledgment request message with the random number generated by the random number generating unit, and to send an acknowledgment message when the acknowledgment is determined as needed, and wherein the collection number comparing unit of the monitoring server determines whether a failure occurs in the multicast network based on a comparison result of the expected number of the acknowledgment messages and the number of the acknowledgment messages actually collected by the collecting unit.