User Manual

AirLink Pro T1/E1 Rack MountInstaller’s Guide
Operations and Maintenance
Rev. B - 1/97
4-6
While indicators provide an observable indication of alarm conditions and
other behavior, the information available through the terminal connected to
the system is easier to access and interpret.
The Event Queue
When an alarm is detected, a message is entered into the AirLink Pro T1/E1
Rack Mount event queue. The event queue is a chronological list of up to 256
events. An alarm event is defined as the declaration of an alarm condition or
the clearing of an alarm condition. The event queue logs the cause and time of
individual alarm events as they occur.
Events Causing an Alarm State
The following events cause an alarm state in the AirLink Pro T1/E1 Rack Mount
and insert an alarm entry in the event queue:
• Receive level below the threshold
• Transmit level below the threshold
• T1 input signal loss
• Error count exceeds the threshold
• Synthesizer loss of lock
• Radio sync loss
• Transmit burst sync loss
Carrier Failure Alarms
The AirLink Pro T1/E1 Rack Mount responds to a carrier failure differently
than devices in a conventional network scheme.
In a conventional network scheme (Figure 4-1), if a cable breaks and disrupts
the network signal, the device immediately downstream from the break detects
the loss of signal and enters a red alarm state.
In the red alarm state, the device sends an unframed, all-ones Alarm Indication
Signal (AIS)—also known as a “blue” signal—toward its downstream neighbor
and a Remote Alarm Indication (RAI), or “yellow “signal back towards its
upstream neighbor.