Ring network system and configuration control method.

摘要

A ring network system in which a plurality of line concentrators (1) each having terminal stations (2) connected thereto through respective branch lines (4) are interconnected through at least one ring transmission lines (3). Each line concentrator includes configuration control switches (7) capable of disconnecting from the ring transmission line all the branch lines placed under control of the line concentrator while holding the ring transmission line in the state to allow communication. The branch line(s) disconnected from the ring transmission line form(s) a local ring through cooperation with an internal transmission line (30). The line concentrator detected abnormality of communication or the line concentrator to be set to the rest state can undergo internal diagnosis operation or continue to be in the rest state without disturbing the communication among other line concentrators. At activation of the line concentrators, any of them may be activated arbitrarily and independently from each other by again connecting the branch lines to the ring transmission lines. <IMAGE>