This attribute displays whether a Loss Of Frame (LOF) alarm state
has been entered. An LOF alarm state is entered when Severely
Errored Frame (SEF) defects have been detected and accumulated
for a period of 2.5 seconds +/- 0.5 seconds. An E3 SEF defect is
reported after detecting Frame Alignment Signal (FAS) errors on 4
consecutive E3 frames received on the incoming line. If the LOF
defects are intermittently occurring, the LOF 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 E3 component goes into an operational state of disabled until
the LOF alarm condition is cleared. The condition is cleared when
E3 framing has been achieved for a period of 10 seconds +/- 0.5
seconds. As long as SEF defects are detected, the node also
transmits the far-end SEF/AIS (in G.751 E3) or FERF (in G.832)
defect indicator over the outgoing line. The txRai attribute is set to
on when transmitting the far-end SEF/AIS defect indicator on the
outgoing line.
The lofAlarm attribute is always set to off when the component has
been locked and left offline.