IP MULTICAST DELIVERY SYSTEM, ITS RATE CONTROLLING METHOD, ITS PROGRAM AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To perform viewing-listening quality protection preventing a packet loss beforehand and to realize selective quality protection and rate control among hierarchical contents.

SOLUTION: When hierarchical contents are on delivery, priority is given among the hierarchical contents and among the hierarchies of the hierarchical contents, and the hierarchical contents are multicast-transmitted. In the output port 8 of a router 5 of IP networks 13 and 14, and the hierarchical contents are allocated among some output queues set up on the priority among the contents. When the data packets of the hierarchical contents are inputted to the output queues, the occupation rates of the output queues are calculated, threshold values set up for the output queues are compared with the calculated occupied parts of the output queues to judge whether the output queues are congested or not. When it is determined that the output queues are congested. data packets where the hierarchical contents are inputted are transferred to a receiving client 9 to notify the congestion state of the networks 13 and 14, and the receiving client 9 who has received the marked data packets detects that the networks 13 and 14 get congested and reduces a receiving rate.

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