This attribute displays whether an AIS (Alarm Indication Signal)
alarm state has been entered. The AIS Alarm state is entered when
AIS defects have been observed and accumulated for 2.5 seconds +/
- 0.5 seconds. An AIS defect is detected after having received less
than 3 zeros in a 2048 bit period (for 8pDS1Atm cards: when both
an Out Of Frame condition exists and a 1's density of at least 99.9%
is present for a time T, where 3 ms T 75 ms; for 8pE1Atm
cards: when both an Out Of Frame condition exists and fewer than
three 0's have been received in 512 bit periods). If the AIS defects
are intermittently occurring, the AIS 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 for the duration
of an AIS alarm state.
The AIS alarm state is cleared when AIS defects are absent for 10
seconds +/- 0.5 seconds.