Step 2: Locate Alarm Indication Signal Alarms
Purpose
An alarm indication signal (AIS) is a valid framed signal with payload containing a repeating 1010 pattern. An AIS alarm indicates a problem with the line upstream from the T1 network element connected to the T1 interface.
Action
To locate the AIS alarm, have the carrier check the T1 network element connected to the T1 interface and trace the problem.
All diagnostics are from the perspective of Router2 (the Juniper Networks router). Figure 4 illustrates the location of an AIS alarm in a T1 network.
What It Means
In Figure 4, the X indicates that there is an LOS or LOF alarm between the repeater and the Tx T1 multiplexer. An AIS alarm is sent from the repeater to Router2.