ISDN Line Simulator User’s Manual
40-400-00012, Rev. E
29
Troubleshooting
Physical Interface
Problem:
U-SYNC LED does not light.
Solution:
The U-SYNC LED is an indicator for the U interface only and will
not light for the S/T interface.
Solution:
Ensure that the device is connected to the U interface and is
2B1Q encoded.
Solution:
Ensure that the U interface is terminated into the NT side of an
NT-1 or TE.
Solution:
Ensure that the terminating device (TE or NT-1) is receiving
power.
Solution:
Ensure that the loop length between the ILS-2000 and the
terminating device is no longer than 1,600 meters.
Problem:
TE indicates no S/T synchronization.
Solution:
Ensure that no more than 300 feet of loop is between the S/T
interface and the TE.
Solution:
Ensure that an NT-1 is not installed between the TE and the ILS-
2000.
Solution:
Ensure that any TE loopback tests are completed or disabled
Problem:
How do I loopback the S/T interface?
Solution:
The S/T interface acts like an NT-1 device; loopbacks are
performed using S and Q subchannel bits per ITU-
TRecommendation I.430.
Problem:
How do I loopback the U interface?
Solution:
Select Loopback as the B Channel setting. Received B-1 and B-
2 channel data is routed to the transmit B-1 and B-2 paths at
each port.