Troubleshooting guide

Section 5, User Interface Guide - UIG-530, M13 Loopbacks
61186003L1-1D 5-93
Figure 5-61. DS3 Line Loopback Test
Digital Loopback
A DS3 Digital Loopback test loops the entire DS3 signal back to the local loop side. The end
effect of this test is a loopback of all T1/E1 signals after being fully multiplexed and demulti-
plexed to and from a DS3 signal. The incoming DS3 data is ignored, and the outgoing DS3
stream is substituted in its place prior to exiting the DS3 framer. Figure 5-62 provides an
illustration of this test.
Figure 5-62. DS3 Digital Loopback Test
DSX-3
LIU
CODEC
(1 of 28)
CODEC
(28 of 28)
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)
M23
MUX/
DMUX
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)