Verilink APS 2000 T1 Line Protection (880-502411-001) Product Manual - Manual (Page 61)

Performance Monitoring
Verilink APS 2000 User Manual 4-9
Out-of-Frame
(OOF) State
An OOF state begins with an OOF event and ends when a reframe
occurs. An OOF state from the network causes a Severely Errored
Second and a Severely Errored Framing Second to be declared.
Alarm Indication
Signal (AIS) State
This state occurs when the CSU detects an AIS in the incoming
signal from the network.
Loss of Frame
(LOF) Alarm State
This state occurs when the CSU detects an LOF alarm (Red Alarm)
on the incoming signal from the network. A loss of frame is
declared when a LOS or OOF occurs continuously for a period of 2
to 3 seconds, and is cleared after 10 seconds without another LOS
or OOF event. For an intermittent LOS at LOF, an integration with a
slope of 1/4 to 1/15 occurs which will declare an LOF alarm when
the integration threshold is reached.
Bit Error Rate (BER) The CSU uses the CRC-6 error events to calculate the bit error rate
for the signal received from the network.