Troubleshooting guide

Section 5, User Interface Guide - UIG-530, M13 Loopbacks
61186003L1-1D 5-85
Data Mode
Select the Data Mode option to end a test in progress.
Tributary
A Tributary loopback loops the selected T1/E1 back to the DS3 network. The T1/E1 signal is
demultiplexed through the M23 and M12/G.747 demultiplexers, looped back, and multi-
plexed back up through the M12/G.747 and M23 multiplexers. During this loopback, all
network receive data is passed to the DSX-1/E1 transmitters, but all data received by the
DSX-1/E1 loop side is ignored and substituted with the network data. Figure 5-52 provides
an illustration of this test.
Figure 5-52. Tributary Loopback Test
Analog Network
An Analog Network loopback test loops the selected T1/E1 back to the DS3 network. The T1/
E1 signal is completely demultiplexed, looped back at the T1/E1 line interface unit (LIU),
through the LIU drivers and receivers, and multiplexed back onto the DS3 network stream.
Figure 5-53 provides an illustration of this test.
Figure 5-53. Analog Network Loopback Test
DSX-3
LIU
CODEC
(1 of 28)
CODEC
(28 of 28)
M23
MUX/
DMUX
D
S
3
F
R
A
M
E
R
M12/G.747
MUX/DMUX
(1 OF 7)
D
S
2
F
R
A
M
E
R
T1/E1 LIU
(1 of 28)
T1/E1 LIU
(28 of 28)