Hi, Gerard.
According to your description, the answer is as follows:
Port B reports the alarm "The feeder fiber is broken or OLT can not receive any expected optical signals(LOS)" all the time because this port is not connected to online ONUs. This standby port is in this state for a long time and therefore it reports the alarm all the time. Though this alarm is cleared manually on the NMS, it is still displayed on the NMS after a manual synchronization or automatic polling synchronization.
Port A (the standby port) generates alarms "The feeder fiber is broken or OLT can not receive any expected optical signals(LOS)" and "The backbone fiber on the port in Type B protection group is broken or the expected optical signal is not detected". After optical signals of port A are detected, port A reports the recovery alarm "The port in Type B protection group receives the expected optical signal".
Port A (the standby port) generates the alarm "The backbone fiber on the port in Type B protection group is broken or the expected optical signal is not detected" indicating that the optical path fails. After optical signals of port A are detected, port A reports the recovery alarm "The port in Type B protection group receives the expected optical signal".
NOTE: In type B protection, the standby port reports the alarm "The feeder fiber is broken or OLT can not receive any expected optical signals(LOS)" all the time, which can be ignored on the NMS. The alarm "The backbone fiber on the port in Type B protection group is broken or the expected optical signal is not detected" indicates that the optical path fails and the fault needs to be located.
Hopes can help you!
