This attribute displays whether an Alarm Indication Signal (AIS)
alarm state has been entered. An AIS alarm state is entered when
AIS defects have been observed and accumulated for 2.5 seconds +/
- 0.5 seconds. An AIS defect is the occurrence of AIS (valid DS3
frame with payload containing the 1010...sequence and with C-Bits
set to zero) in contiguous M-frames for a time greater than 100
milliseconds. 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 DS3 component goes into an operational state of disabled until
the AIS alarm condition is cleared (after AIS has been no longer
detected for a period of 10 seconds +/- 0.5 seconds). As long as AIS
is detected, the node also transmits the far-end SEF/AIS defect
indicator over the outgoing line. When not running in C-Bit Parity
mode, the txRai attribute is also set to on when transmitting the far-
end SEF/AIS defect indicator on the outgoing line.
The rxAisAlarm attribute is always set to off when the component
has been locked and left offline.