It is known that the difference threshold of the main channel and the standby channel is 5dB initial optical power, and both the main channel and the standby channel are 2dBm. Due to the increase of…

It is known that the difference threshold of the main channel and the standby channel is 5dB initial optical power, and both the main channel and the standby channel are 2dBm. Due to the increase of the optical fiber loss of the main channel, the optical power of the main channel becomes -4dBm. The standby channel remains unchanged. In this case, optical line protection switching will be triggered.