Nortel Networks Circuit Card - Manual (Page 292)

Page 292 of 906 NT5D33 and NT5D34 Lineside E1 Interface cards
553-3001-211 Standard 3.00 August 2005
The duration value is set in seconds and can be set from 1 to 3,600 seconds (1
hour). This duration value indicates how long the alarm condition must last
before an alarm will be declared. 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 above10
6
. Higher bit-error rates are restricted to shorter
durations because the MMI error counter fills at 65,000 errors.
The alarm indications (LEDs and external alarm contacts) will clear
automatically after the specified period, or duration, has expired if the Set
Clearing (S C) “Enable Self Clearing” option has been set. Otherwise, the
alarm will continue until the command Clear Alarm (C A) has been
entered.
When an alarm is cleared, all activity caused by the alarm indications is
cleared:
• the external alarm hardware is deactivated (the contact normally open
will be reopened)
• the LED goes out
• an entry is made in the alarm log of the date and time the alarm was
cleared
• carrier-fail line supervision ceases (for alarm level 2 only)
If self-clearing alarm indications have been disabled, carrier-fail line
supervision terminates when the alarm condition has ceased, but the external
alarm contact and faceplate LED remain active until the alarm is cleared.
A heavy bit-error rate can cause 200 bit errors to occur much more quickly
than100 seconds. This causes the alarm to be declared sooner.
10
-8
2.0/100 seconds 100-3600 seconds
10
-9
2.0/1000 seconds 1000-3600 seconds
Table 106
E1 bit error rate threshold settings (Part 2 of 2)
Alarm threshold bit
errors per second in
power of 10
Threshold to set
alarm
Allowable Duration
Periods