Nortel Networks Circuit Card 311 - Manual (Page 241)

Man-Machine T1 maintenance interface software 241
Alarm Threshold
bit errors per second
in Power of 10
Threshold
to set alarm
Allowable
Duration Periods
10 –7 1.5/10 seconds 10–3600 seconds
10 –8 1.5/100 seconds 100–3600 seconds
10 –9 1.5/1000 seconds 1000–3600 seconds
The duration value is set in seconds and can be set from 1 to 3600 seconds
(1 hour). This duration value indicates how long the alarm lasts. Low bit
error rates (10-7 through 10-9) are restricted to longer durations since it
takes more than one second to detect an alarm condition above 10-6.
Higher bit error rates are restricted to shorter durations because the MMI
error counter fills at 65,000 errors.
If the Set Clearing (S C) "Enable Self Clearing" option is set, the alarm
indications (LEDs and external alarm contacts) clear automatically after the
duration period expires. Otherwise, the alarm continues until the command
set Clear Alarm (C A) is entered.
When an alarm is cleared, the following activity caused by the alarm is
cleared:
• the external alarm hardware is deactivated (the contact normally open
is reopened)
• the LED light turns off
• an entry is made in the alarm log of the date and time when the alarm is
cleared
• carrier fail line supervision ceases (for alarm level 2 only)
If self-clearing alarm indications are disabled, carrier fail line supervision
terminates when the alarm condition is ceased, but the alarm contact and
faceplate LED remains active until the alarm is cleared.
Note: A heavy bit error rate can cause 150 bit errors to occur in less
than 100 seconds. This causes the alarm to be activated sooner.
An alarm is not automatically cleared until the system no longer detects the
respective bit error threshold during the corresponding duration period.
For example, if an AL1 threshold of 6 (representing 10–6) and a duration
period of 100 seconds is specified, an alarm is activated if more than 150
bit errors occur in any 100 second period (1.5 seconds X 100 seconds
= 150/100 seconds). As soon as the alarm is activated, the bit counter
is reset to 0. If the next 100 seconds pass, and less than 150 bit errors
are detected, then the alarm clears after the duration period. However, if
more than 150 bit errors are detected in the next 100 seconds, the alarm
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 01.04 Standard
Release 5.0 23 May 2008
Copyright © 2003-2008, Nortel Networks
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