| 摘要 |
PURPOSE:To switch normally a transmission line even when an abnormal signal exists on a spare transmission line beforehand by prohibiting the supervision of a loop abnormality until the abnormal signal on the spare transmission line switched is removed at the time of switching to the spare transmission line. CONSTITUTION:A loop connecting device 10 is composed of a connecting part 11 and a control part 12. The connecting part 11 connects and relays a present-use transmission line 21 and a spare transmission line 22. The control part 12 is connected to the connecting part 11 and executes the supervision and the control of transmission lines 21 and 22. When the loop abnormality is detected by the control part 12, after the connecting part 11 is controlled and switching is executed from the present-use transmission line 21 to the spare transmission line 22, a timer in the control part 12 is started and the supervision of the loop abnormality of the switching spare transmission line is prohibited for the rescribed time (initial supervising condition). When some frame is detected by the initial supervising condition, the initial supervising condition is released. After the timer is timed out and the initial supervising condition is completed, the initial signal is sent onto the spare transmission line 22, the spare transmitting line 22 is initialized, the abnormal signal, etc., on the transmission line are removed and the control part 12 starts the supervision of the transmitting line.
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