Nortel Networks 1000 - Manual (Page 235)

Man-Machine T1 maintenance interface software 235
Alarm Level 2 threshold value: E-5 Threshold duration (in seconds): 1
Frame slips alarm level threshold: 5 Threshold duration (in hours): 2
Current dip switch S1 settings (S1..S8) On Off Off On Off Off Off On
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” (page 227) . Bit errors may
activate either a level 1 or level 2 alarm. 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 has been 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.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.