EXFO FTB-8510B Guia Del Usuario página 929

Alarm Analysis
Possible alarms that can be detected are:
OOF (Out-OF-Frame): A OOF error indicates that four consecutive
frame bit errors are detected.
RAI (Yellow) (Remote Alarm Indication):
For SF framing: The RAI alarm is declared when bit 2 in each timeslot
contains "0".
For ESF framing: The RAI alarm is declared when eight "ones"
followed by eight "zeros" pattern is received continuously in the data
link (FDL).
AIS (Alarm Indication Signal): The AIS alarm is declared when an
unframed all-ones signal is received.
SONET/SDH Application
DSn Tabs
DS1/1.5M RX
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