| 摘要 |
PURPOSE:To duplicate completely networks by providing a relay function of an information signal between node equipments to a transmission line access section so as to duplicate the system independently of a transmission medium. CONSTITUTION:The constitution is adapted that a detection signal of a power failure, clock or relay function fault in transmission access sections 5, 6 and a fault of node control sections 7, 8 is fed to a duplication changeover control section 9. If the detection signal is inputted to the duplication changeover control section 9 because of the occurrence of any fault, when the fault takes place in a node equipment of the active system and the node equipment of the standby system is normal, a changeover command is given to the duplication changeover control section 9, which gives a command of bypassing the transmission line access section 5 or 6 of the node equipment of the standby system and switching a switch circuit 10 of a line adaptor. When both the node equipments are normal, the node equipment receiving the command of active system continues the operation.
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