Question

The port-based GPON type B protection configured on an OLT implements protection for primary/secondary backbone optical paths.

Context: Port A and port B on a Huawei GPON OLT are configured into a protection group, in which, port A is the active port and port B is the standby port. Furthermore, port A is connected to ONUs that go online normally.

Normally, whether port B reports the alarm "The feeder fiber is broken or OLT can not receive any expected optical signals(LOS)" all the time and whether this alarm persists after being cleared manually on the NMS?
If an active/standby switchover is triggered by CLI or optical path, then port A serves as the standby port and port B serves as the active port, what alarms are reported by port A?
Remove the optical fiber connected to port A (the standby port). Do alarms reported by port A change?
Answer

Port B reports the alarm "The feeder fiber is broken or OLT like Huawei MA5800 X7 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".