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Table 3-3: Summary of SONET Statistics (continued)
Statistic
PLM-P event counter
SF BER event counter
SD BER event counter
SONET Events
The PoS module can detect and report a variety of error and alarm conditions, some of
which also trigger actions on the SONET link. Table 3-4 describes these events and their
associated actions. Syslog messages are output for these events.
Table 3-4: SONET Events
Event
Loss of Signal (LOS)
Loss of Frame (LOF)
Loss of Pointer (LOP)
Alarm Indication
Signal—Line (AIS-L)
Packet Over SONET Module Installation and User Guide
Description
Number of PLM-P events
Number of SF BER events
Number of SD BER events
Description
Loss of Signal is detected by the Section Terminating Equipment
(STE) when an all-zeroes pattern on the incoming SONET signal
lasts 100 microseconds or longer. This condition can be caused by
loss of light.
SONET Action: Send RDI-L upon LOS detection.
Loss of Frame is detected by the STE when a Severely Errored
Framing (SEF) defect on the incoming signal persists for 3
milliseconds.
Related SONET Overhead: A1, A2 (framing pattern).
SONET Action: Send RDI-L upon LOF detection.
The Path Loss Of Pointer event is detected as a result of excess
New Data Flags (NDFs) or invalid pointers in the H1/H2 fields of the
received signal.
Related SONET Overhead: H1,H2 contain NDF and pointer.
SONET Action: Send RDI-P upon LOP detection.
The Line Alarm Indication Signal is sent by the upstream STE to
inform the LTE that a LOS or LOF defect has been detected.
Extreme's SONET module never sends AIS-L. AIS-L was formerly
known as Line Far End Receive Failure (FERF).
Related SONET Overhead: K2 carries AIS-L.
SONET Action: Send RDI-L upon reception of AIS-L.
Configuring and Monitoring SONET Ports
3-19
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