This attribute indicates whether a LOS (Loss of Signal) alarm state
has been entered. A LOS alarm is declared after LOS defects have
been observed and accumulated for a period of 2 seconds +/- 0.5
second . A LOS defect is detected upon observing all zeros for 150
ms . If the LOS defects are intermittently occurring, the LOS defect
accumulator is decremented at a rate of 1/10 of the incrementing
rate (alarm integration ratio of 1/10), with all measurements based
on a 200 ms polling cycle.
The port goes into an operational state of disabled until the LOS
alarm state is cleared. The LOS alarm state is cleared when LOS
defects are absent for 10 seconds +/- 0.5 second.