Hitachi, Ltd.

Yasuhiro Nagai

Michio Suzuki

Ryoichi Sasaki

Noboru Mizuhara

Shunichi Yosioka

The communication system has a plurality of sub-networks, for example composed of transmission communication nodes, PBX communication notes, application communication nodes, and the like, respectively. Each of these sub-networks is managed by a management system, and all of the management systems are managed by an integrated management system. Each communication node is autonomously provided with the function of establishing an emergency routing as a first stage routing control on the occurrence of a failure in a circuit affecting the communication node. The autonomous routing is heirarchial with respect to node types. Failure and the influences of failure are reported to the sub-network management systems, which in turn can report to the integrated management system. As a second stage of routing control, one or more of the management systems establishes a global routing to replace the emergency local routing. The global routing may take effect if the managment system determines that the failure cannot be corrected within a substantially fixed period of time.

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Bunkyo, Japan

Yasuhiro Nagai