2.0 Mb DTI alarms
There are two groups of alarm indicators monitored by the 2.0 Mb DTI. Within these two alarm
groups, there are several individual alarm types.
Group 1 alarms are event-driven and include indicators that decrement a counter whenever
an error is detected. Grade-of-service is changed based on how quickly the threshold of the
counter is exceeded.
The threshold count is determined in LD 73 and downloaded to the 2.0
Mb DTI. Group 1 alarms are:
1. Bipolar Violations (BPV) — Near-end alarm
2. Slips (SLP) — Near-end alarm
3. Frame Alignment Problems (FAP) — Near-end alarm
4. Cyclic Redundancy Check (CRC-4) — Near-end alarm
Group II alarm indicators are either continuous or discontinuous. Grade-of-service is changed
based on the duration of the alarm within a defined period of time. A minimum persistence time
is defined in LD 73 and downloaded to the 2.0 Mb DTI.
Group II alarm types are listed from high to low priority. A Group II alarm type might not be
reported when a greater type is detected.
1. Alarm Indication Signal (AIS) — Far-end alarm
2. Loss of Frame Alignment Signal (LFAS) — Near-end alarm
3. Loss of Multiframe Alignment Signal (LMAS) — Near-end alarm
4. Loss of CRC-4 Multiframe Alignment Signal (CFAS) — Near-end alarm
5. Remote Alarm Indication (RAI, B3) — Far-end alarm
6. Remote Yellow Alarm (B6) — Far-end alarm
7. Alarm Indication Signal, 64 Kilobit (AIS 64) — Far-end alarm
Group 1
Bipolar Violation (BPV). In a bipolar pulse stream, pulses alternate in polarity. A bipolar violation
has occurred if, after transmission, two pulses of the same polarity are received in succession
(this could be caused by an electrical disturbance such as noise). See
Figure 29: Bipolar
violations on page
133.
2.0 Mb DTI maintenance
132 ISDN Primary Rate Interface Maintenance November 2011
Comments? infodev@avaya.com
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