| 摘要 |
PROBLEM TO BE SOLVED: To automatically monitor the state of a spare line, also to reliably detect a fault that can be relieved by switching and also to efficiently operate a line depending on the detected results. SOLUTION: Sender side MSOH monitor circuits 3-1 to 3-N monitor K2 bytes in the MSOH of the SDH frame of each input data string, supply N pieces of detected results of obtained MS-AIS to a spare line frame multiplex circuit 50, performs frame multiplexing and transmit the detected results to a receiving side. Switching signal generation circuits 12-1 to 12-N generate a switching signal that controls receiving switching circuits 8-1 to 8-N and sandier switching circuits 4-1 to 4-N on the basis of detected results obtained from radio frame detection circuit 7-1 to 7-N and a spare radio frame detection circuit 70 and N pieces of detected results of the MS-AIS included in received data from the circuit 70, and does not perform switching when a transmitting side detects the MS-AIS even in the case of detecting the fault of a radio frame and MS-AIS. |
