| 摘要 |
PROBLEM TO BE SOLVED: To provide a presence service guaranteeing distribution of important information even at congestion.SOLUTION: In a congestion control system 1, an identification device 3 searches for seventh-level (application layer) information of the OSI basic reference model of IP-packetized communication data transmitted from a user terminal 2, so as to analyze whether or not the communication data includes important information. The identification device 3 then determines the priority of the communication data on the basis of the analysis result, to set the priority into an IP header as third-level information of the OSI basic reference model. When a presence server 5 falls in a congestion state, a NW device 4, such as a router, that handles third-level information, not only a device of a server system (including the presence server 5) that handles seventh-level information, controls communication data quantity on the basis of the priority of the communication data requesting the presence server 5 to process. |
