| 摘要 |
PURPOSE:To execute the switching service of an optical transmission line for enlarging a capacity substantially with no interruption by providing an auxiliary optical transmission line between a center and a subscriber. CONSTITUTION:The center 1 and the subscriber 3 are connected by the optical transmission line 2-1 for an up line, and the optical transmission line 2-2 for a down line large in the capacity from the center 1 side. The auxiliary optical transmission lines 2-3, 2-4 are provided as well as these transmission lines 2-1, 2-2. At the time of switching the optical transmission line in order to enlarge the capacity, when the transmission lines 2-3, 2-4 are previously used, after the completion of a test requiring a long period, the transmission lines 2-1, 2-2 are switched to the transmission lines 2-3, 2-4, the optical transmission line can be switched substantially with no interruption of the service. After switching, the transmission lines 2-1, 2-2 become the auxiliary transmission line. |
