Nortel Networks 553-3001-211 manual 290 of 894 NT5D33 and NT5D34 Lineside E1 Interface cards

Page 290 of 894 NT5D33 and NT5D34 Lineside E1 Interface cards

seconds, neither a loss of signal, out-of-frame condition, or blue alarm condition occurs.

If a repeating device loses signal, it immediately begins sending an unframed signal of all ones 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, or blue alarm condition occurs.

Alarm Disable

The Alarm Disable (A D) command disables the external alarm contacts. When this command is typed, the MMI displays the message Alarms Disabled and the MAINT LED lights. In this mode, no yellow alarms are sent and the LEI does not enter line processing mode. Alarm messages are sent on the MMI terminal and the LED continues to indicate alarm conditions.

Alarm Enable

The Alarm Enable (A E) command does the reverse of the Alarm Disable (A D) command. It enables the external alarm contacts. When this command is typed in, the MMI will display the message Alarms Enabled. In this mode, yellow alarms can be sent and the LEI can enter line processing mode.

Clear Alarm

The Clear Alarm (C A) command clears all activity initiated by an alarm: the external alarm hardware is deactivated (the contact normally open is reopened), the LED goes out, an entry is made in the alarm log of the date and time the alarm was cleared, and line processing ceases (for alarm level 2 only). When this command is typed, MMI displays the message Alarm acknowledged. If the alarm condition still exists, an alarm is declared again.

Display Alarms

A detailed report of the most recent 100 alarms with time and date stamps can be displayed by entering the Display Alarms (D A) command into the MMI, which will cause a screen similar to Figure 50 on page 291 to appear.

553-3001-211 Standard 2.00 September 2004