| 摘要 |
PURPOSE:To improve the relieving rate of a supervising signal at carrier line fault by transmitting supervisory signals in parallel via a service signal region of plural lines at a transmitting side and selecting and receiving the service signal region of normal lines among plural lines at reception side. CONSTITUTION:A supervisory signal of a line switching device 1 is transmitted to a line switching device 2 via carrier lines 3-1-3-n while connecting service signal lines 10-1-10-n in parallel. In the line switching device 2, service signal lines 11-1-11-n receiving the supervisory signal are connected to a changeover switch SW of a selector 13 and a service signal line of the normal carrier line is selected. Thus, the supervisory signal of the line switching device 1 is received by the line switching device 2 when even one normal line exists in the carrier lines 3-1-3-n, and the state of the switching element or the like of the line switching device 1 is supervised. |
