Alarm Operation And Reporting - Avaya Nortel Communication Server 1000 Reference

NT5D11 and NT5D14 Lineside T1 Interface cards
Current dip switch S2 settings (S1..S8) On Off On Off Off
Off On Off

Alarm operation and reporting

The MMI monitors the T1 link according to the parameters established through the Set Alarm
command set for the following conditions:
• Excessive bit error rate
• Frame slip errors
• Out of frame condition
• Loss of signal condition
• Blue alarm (AIS) condition
Descriptions of the excessive bit error rate and frame slip errors conditions can be found in
Configuring parameters
The remaining conditions, when detected, always cause the system to activate a level 2
alarm.
An out of frame condition is declared if two out of four frame bits are in error. If this condition
occurs, the hardware immediately attempts to reframe. During the reframe time, the T1 link is
declared out of frame, and silence is sent on all receive timeslots.
A loss of signal condition is declared if a full frame (192 bits) of consecutive zeros is detected
at the receive inputs. If this condition occurs, the T1 link automatically attempts to
resynchronize with the distant end. If this condition lasts for more than two seconds, a level 2
alarm is declared and silence is sent on all receive timeslots. The alarm is cleared if, after two
seconds, neither a loss of signal, out of frame condition, nor blue alarm condition occurs.
If a repeating device loses signal, it immediately begins sending an unframed all 1's signal to
the far-end to indicate an alarm condition. This condition is called a blue alarm, or an Alarm
Indication Signal (AIS). If an AIS is detected for more than two seconds, a level 2 alarm is
declared, and silence is sent on all receive timeslots. The alarm is cleared if, after two seconds,
neither a loss of signal, out of frame condition, nor blue alarm condition occurs.
Alarm Disable
The Alarm Disable (A D) command disables the external alarm contacts. When this command
is typed, the MMI displays the message "Alarms Disabled" and the MAINT LED turns on. In
this mode, no yellow alarms are sent and the Lineside T1 card does not enter line processing
mode. Alarm messages are still sent to the MMI terminal and the LED light continues to indicate
alarm conditions.
Alarm Enable
The Alarm Enable (A E) command set does the opposite of the Alarm Disable command set.
It enables the external alarm contacts. When this command set is typed in, the MMI displays
184 Circuit Card Reference
on page 180. Bit errors may activate either a level 1 or level 2 alarm.
Comments? infodev@avaya.com
July 2011