Control system for configuring ring LAN with improved reconfiguration operation

摘要

In a ring LAN system having a configuration control unit serially connected to a dual ring transmission line, the configuration control unit is provided with a transmission line reconfiguration control mechanism to disconnect a fault point upon detection of a transmission fault, such as a breaking of one of a twisted pair of cables, and after recovery of the fault, reconnect the disconnected point to restore the transmission line to its original state. The reconfiguration control mechanism suspends reconfiguration control if a reconfiguration operation counter counts more than a predetermined number of reconfiguration operations within a predetermined time period measured by a reconfiguration operation monitor timer, such as when a temporary fault occurs intermittently. However, operation of such reconfiguration control suspension is initially suspended after system start up, such as when transmission line signals are attenuated and appear as faults, until after an elapsed time after system start up measured by a lapse time timer reaches a preselected time period. Operation of the reconfiguration control mechanism is controlled by a reconfiguration management mechanism.