Nortel Networks 553-3001-211 manual NT5D33 and NT5D34 Lineside E1 Interface cards Page 243

NT5D33 and NT5D34 Lineside E1 Interface cards Page 243 of 894

condition. Depending on how the Man Machine Interface (MMI) is configured, this LED will remain lit until one the following actions occur:

•If the “Self-Clearing” function is enabled in the MMI, the LED will clear the alarm when the alarm condition is no longer detected. This is the factory default configuration.

•If the “Self-Clearing” function has not been enabled or it has been subsequently disabled in the MMI, the LED alarm indication will stay lit until the command “Clear Alarm” has been typed in the MMI, even though the carrier automatically returned to service when the alarm condition was no longer detected.

The YELLOW ALARM LED indicates that the LEI has detected a yellow alarm signal from the terminal equipment side of the E1 link. See “Man-Machine E1 maintenance interface software” on page 272 for information on E1 link maintenance. If the terminal equipment detects a red alarm condition such as not receiving a signal, or the signal exceeds bit-error thresholds or frame-slip thresholds, a yellow alarm signal is sent to the LEI, if the terminal equipment supports this feature. If a yellow alarm signal is detected, this LED will light.

The MAINT LED indicates if LEI is fully operational because of certain maintenance commands that are issued through the MMI. See “Man-Machine E1 maintenance interface software” on page 272 for information on E1 link maintenance. If the card detects that tests are being run or that alarms have been disabled through the MMI, this LED will light and will remain lit until these conditions are no longer detected, then it turns off.

Functional description

Figure 39 on page 244 shows a block diagram of the major functions contained on the LEI card. Each of these functions is described on the following pages.

Circuit Card Description and Installation