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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.
