Nortel Networks 1000 - Manual (Page 229)

Man-Machine T1 maintenance interface software 229
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
clears
•
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 ceases, but the alarm contact and
faceplate LED remain 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
continues for the designated duration period. The alarm finally clears
when the alarm condition is no longer detected for the designated duration
period either by self-clearing (if this function is enabled), or when the Clear
Alarm (C A) command set is entered.
In addition to bit errors, the Set Alarm function configures parameters
for detecting frame slip errors, by establishing a threshold necessary to
activate an alarm. If the threshold value is exceeded, a level 2 alarm is
activated. The frame slip threshold can be specified from 1 to 255 frame
slips per time period. The duration time period can be specified from 1 to
24 hours.
Nortel Communication Server 1000
Circuit Card Reference
NN43001-311 02.06 Standard
27 August 2008
Copyright © 2003-2008 Nortel Networks
.