Some optical ports reported the IN_PWR_ABN alarm, which indicated that the input optical power was abnormal, because optical modules were not securely installed. The fault was rectified by re-installing optical modules.
Product

OptiX OSN 3500
Fault Type

IN_PWR_ABN
Connection fault
Symptom

Some optical ports on a line board reported the IN_PWR_ABN alarm. The NMS showed that the input optical power at those optical ports was too high.
NOTE:
Generally, an optical port reports the LSR_NO_FITED alarm indicating that a laser is not installed if the optical module is not securely installed or is faulty. However, in this case, the optical ports reported the IN_PWR_ABN alarm instead of the LSR_NO_FITED alarm.
Cause Analysis

The possible causes are as follows:
The input optical power was too high.
The optical ports were faulty.
The input power detection circuits on the line board were faulty.
The optical modules were not securely installed.
The optical modules were faulty.
Procedure

Viewed the IN_PWR_ABN alarm on the NMS and determined the ID of the alarmed port (assuming that the alarmed port was A and it housed optical module C).
Measured the input optical power at optical port A using an optical power meter. The meter reported that the input optical power at optical port A was normal. Therefore, this issue was not related to the input optical power.
Removed optical module C and inserted it into optical port B. Optical port B did not report the IN_PWR_ABN alarm. Therefore, this issue was not related to optical module C.
Re-inserted optical module C into optical port A. Optical port A did not report the IN_PWR_ABN alarm, and the input optical power was normal. Therefore, the cause of this issue was that the optical module was not securely installed.
Related Information

None