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CHAPTER 6 PHY FUNCTION
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Table 6-7. Alarms and Failures (1/2)
LOS (Loss Of Signal)
Loss of receive signal
Detection: When patterns of all 0 or all 1 are received continuously for about 80
μ
s
Clear:
When the LOS condition cannot be detected for 125
μ
s
OOF (Out Of Frame)
Out of frame synchronization
Detection: When a frame synchronization pattern (A1, A2) error in the receive data is detected in four successive
frames
Clear:
When a frame synchronization pattern is detected in two successive frames
LOF (Loss Of Frame)
Loss of frame
Detection: When OOF status lasts for 3 ms
Clear:
When status out of OOF status lasts for 3 ms
LOP (Loss Of Pointer)
Pointer failure detection
Detection: When a frame having an invalid pointer value is received eight times continuously. When OOF is
detected, LOP status is forcibly set.
Clear:
When a frame having a valid pointer is received three times continuously
OCD (Out of Cell Delineation)
Out of cell delineation
Detection: When seven cells, having a header in which an error is detected in the HEC verification result, are
received continuously. When OOF, LOP, or AIS is detected, OCD status is forcibly set.
Clear:
When seven cells having a valid header are received continuously
LCD (Loss Of Cell Delineation)
Loss of cell delineation
Detection: When OCD status continues for 4 ms
Clear:
When cell synchronization status continues for 4 ms
Line AIS (Line Alarm Indication Signal)
Line alarm indication signal. Detects the occurrence of Line AIS in the unit at the transmission source (upstream).
Detection: When five frames, with the overhead K2 byte (6th through 8th bits) set to "111", are received continuously
Clear:
When five frames, with the overhead K2 byte (6th through 8th bits) not set to "111", are received
continuously
Path AIS (Path Alarm Indication Signal)
Path alarm indication signal. Detects the occurrence of Path AIS at the transmission source (upstream).
Detection: When three frames for which the overhead H1 and H2 bytes are all 1 are received continuously
Clear:
When three frames with NDF (New Data Flag) set to "0110" are received continuously with the same valid
pointer value, or when LOP status is detected when one frame for which NDF is "1001" is received with a
valid pointer value