Troubleshooting guide

MX2820 System Manual
5-86 61186003L1-1D
Digital Line/Net
A Digital Line/Net loopback performs a loopback of the selected T1/E1 in both the network
and local loop directions. Both loopbacks occur at the T1/E1 LIU. The network side loopback
occurs at the edge of the LIU, while the T1/E1 loop side loopback occurs within the LIU
through the receiver, receive equalizer, transmit jitter attenuator, and through the T1/E1
transmit drivers. Figure 5-54 provides an illustration of this test.
Figure 5-54. Digital Line/Net Loopback Test
CODEC Line/Net
A CODEC Line/Net loopback performs a loopback of the selected T1/E1 line in both the
network and local loop directions. Both loopbacks occur at the T1/E1 CODEC. Both the
network and the local loop side of the loopback are executed at the edge of the CODEC, which
completely tests the M13 MUX and the T1/E1 LIU. Figure 5-55 provides an illustration of this
test.
Figure 5-55. CODEC 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)
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