OOF (Out-Of-Frame) Condition -- Red Alarm
framing pattern. Depending upon the equipment, this can occur when 2 of 4,
2 of 5, or 3 of 5 framing bits are in error. A reframe clears the OOF
condition. Cause of RED ALARMS.
Red CFA (Carrier Failure Alarm) -- Red Alarm
Occurs after detection of CONTINUOUS OOF condition for 2.5 seconds. This alarm state is cleared
when no OOF conditions occur for AT LEAST 1 second. Some applications (AT&T DACS services) may not
clear the CFA state for UP TO 15 seconds of NO Out-Of-Frame occurences.
Yellow CFA (Carrier Failure Alarm) -- Yellow Alarm
(If received indicates that somewhere down the line there is equipment that is in RED ALARM i.e.
no receive)When a Terminal/Network equipment enters a RED Alarm state, it transmits a "Yellow
Alarm" in the opposite direction. A Yellow Alarm is transmitted by setting Bit #2 of each
timeslot to a 0 (zero), SPACE state for D4 Framed facilities. For ESF facilities, a Yellow Alarm
is transmitted by sending a repetitive 16-bit pattern consisting of 8 MARKS (1) followed by 8
SPACES (0) in the Datalink bits. This is transmitted for a MINIMUM of 1 second.