Locate Most Common T1 Alarms and Errors
To locate common alarms and errors, follow these steps:
- Locate Loss of Signal and Loss of Frame Alarms
- Locate Alarm Indication Signal Alarms
- Locate an Incoming Yellow Alarm
Locate Loss of Signal and Loss of Frame Alarms
Problem
A loss of signal (LOS) or loss of frame (LOF) alarm indicates that a signal could not be detected at the T1 interface.
Solution
To locate the LOS or LOF alarm, check the connection between the router port and the first T1 network element. In the example network in Figure 1, the X indicates that there is a connection problem between Router2 and the nearest T1 network element.
Figure 1: Location of an LOS or LOF Alarm in a T1 Network
 | Note: Tx represents the transmit port and Rx represents the receive port. |
Sample Output
user@router2> show interfaces t1-1/1/1 extensive[... Output truncated...]
DS1 alarms : LOF, LOS
DS1 defects : LOF, LOS
T1 media : Seconds Count State
SEF 32 0 Defect Active
BEE 0 0 OK
AIS 0 0 OK
LOF 32 0 Defect Active
LOS 32 0 Defect Active
YELLOW 0 0 OK
BPV 0 0
EXZ 0 0
LCV 0 0
PCV 32 10667
CS 0 0
LES 0
ES 32
SES 32
SEFS 32
BES 0
UAS 32
[...Output truncated...]
Meaning
The sample output shows that Router 2 (Rx) detected a cumulative LOS and LOF alarm for 32 seconds.
Locate Alarm Indication Signal Alarms
Problem
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.
Solution
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 Router 2 (the Juniper Networks router). Figure 2 illustrates the location of an AIS alarm in a T1 network.
Figure 2: Location of an AIS Alarm in a T1 Network
Meaning
In Figure 2, 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 Router 2.
Locate an Incoming Yellow Alarm
Problem
An incoming yellow alarm indicates that the T1 network element connected to the T1 interface has a problem with the signal it is receiving from the T1 interface.
Solution
To locate the yellow alarm, check the cable between the T1 interface and the directly connected T1 network element.
All diagnostics are from the perspective of Router 2. Figure 3 illustrates the location of a yellow alarm in a T1 network.
Figure 3: Location of a Yellow Alarm in a T1 Network
Meaning
In Figure 3, the T1 multiplexer detects an LOS or LOF alarm on its connection from Router 2 and sends a yellow (YLW) alarm to Router 2.
