Nortel Networks Circuit Card - Manual (Page 234)

Page 234 of 906 NT5D11 and NT5D14 Lineside T1 Interface cards
553-3001-211 Standard 3.00 August 2005
Clearing” option has been set. Otherwise, the alarm will continue until the
command set Clear Alarm (C A) has been entered.
When an alarm is cleared, the following activity caused by the alarm will be
cleared:
• the external alarm hardware will be deactivated (the contact normally
open will be reopened)
• the LED light will go out
• an entry will be made in the alarm log of the date and time the alarm was
cleared
• carrier fail line supervision will cease (for alarm level 2 only)
If self-clearing alarm indications have been disabled, carrier fail line
supervision will terminate when the alarm condition has ceased, but the alarm
contact and faceplate LED will 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 will cause the alarm to be activated sooner.
An alarm will not be 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 will be 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 will clear 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 will finally clear 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 will be 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.