Nortel Meridian 1 Option 11C Manual page 69

Group II alarm types are listed from high to low priority. A Group II alarm
type may 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).
Figure 8
Bipolar violations
Normal
Error
Cyclic Redundancy Check (CRC-4) When the 2.0 Mb DTI card is running
in CRC-4 mode, the CRC-4 word contains a checksum of all data in the
multiframe. The receiving side uses the checksum to verify the data.
DTI Maintenance
Option 11C
Page 69 of 126
553-8300.EPS
2.0 Mb DTI/PRI