When the intra-board 1+1 protection is configured on the LWXD board, the IN1/OUT1 functions as the working channel, and the IN2/OUT2 functions as the protection channel. After the services are accessed, the alarms, performance events, and services on the working and protection channels are normal. After the services on the working channel are switched to the protection channel forcibly, the B1 bit error occurs in the protection channel. No bit error occurs in the protection channel before the switching, but the B1 bit error occurs in the protection channel after the switching. Why?
The LWXD board is a dual-fed and selective receiving board. One transmit module on the WDM side transmits signals dually through the splitter. There are two receive modules. Normally, the signals of one receive module are received selectively for detection. The performance of the electrical layer on the protection channel cannot be checked (The B1 bit error is a signal at the electrical layer). The related alarms and performance events only at the optical layer can be detected, such as the R_LOS alarm and the optical power. Therefore, the LWXD board cannot accurately determine the bit error status on the non-working channel. The services on the non-working channel must be switched to the working channel forcibly. Then, the performance of the channel can be determined according to the performance analysis.