Adtran MX2800 M13 User Manual
MX2800 M13 Multiplexer User Manual
Loopbacks, Section 6
61200290L1-1G
6-3
Figure 6-3. Tributary Loopback Test
Analog Network
An Analog Network
loopback test loops the selected T1/E1 back to the network (DS3). The T1/E1 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. See
receivers, and multiplexed back onto the DS3 network stream. See
for an illustration of this
test.
Figure 6-4. Analog Network Loopback
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 deep into the LIU through the receiver, receive equalizer,
transmit jitter attenuator, and the T1/E1 transmit drivers. See
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 deep into the LIU through the receiver, receive equalizer,
transmit jitter attenuator, and the T1/E1 transmit drivers. See
this test.
Figure 6-5. Digital Line/Network Loopback
DSX-3
LIU
M23
MUX/DMUX
M12/G.747
MUX/DMUX
(1 of 7)
F
R
A
M
E
R
D
S
2
F
R
A
M
E
R
D
S
3
....
....
T1/E1 LIU
(1 of 28)
CODEC
(28 of 28)
CODEC
(1 of 28)
T1/E1 LIU
(28 of 28)
DSX-3
LIU
M23
MUX/DMUX
M12/G.747
MUX/DMUX
(1 of 7)
F
R
A
M
E
R
D
S
2
F
R
A
M
E
R
D
S
3
....
T1/E1 LIU
(1 of 28)
CODEC
(28 of 28)
CODEC
(1 of 28)
T1/E1 LIU
(28 of 28)
DSX-3
LIU
M23
MUX/DMUX
M12/G.747
MUX/DMUX
(1 of 7)
F
R
A
M
E
R
D
S
2
F
R
A
M
E
R
D
S
3
....
....
T1/E1 LIU
(1 of 28)
CODEC
(28 of 28)
CODEC
(1 of 28)
T1/E1 LIU
(28 of 28)
DSX-3
LIU
M23
MUX/DMUX
M12/G.747
MUX/DMUX
(1 of 7)
F
R
A
M
E
R
D
S
2
F
R
A
M
E
R
D
S
3
....
T1/E1 LIU
(1 of 28)
CODEC
(28 of 28)
CODEC
(1 of 28)
T1/E1 LIU
(28 of 28)
DSX-3
LIU
M23
MUX/DMUX
M12/G.747
MUX/DMUX
(1 of 7)
F
R
A
M
E
R
D
S
2
F
R
A
M
E
R
D
S
3
....
....
T1/E1 LIU
(1 of 28)
CODEC
(28 of 28)
CODEC
(1 of 28)
T1/E1 LIU
(28 of 28)
DSX-3
LIU
M23
MUX/DMUX
M12/G.747
MUX/DMUX
(1 of 7)
F
R
A
M
E
R
D
S
2
F
R
A
M
E
R
D
S
3
....
T1/E1 LIU
(1 of 28)
CODEC
(28 of 28)
CODEC
(1 of 28)
T1/E1 LIU
(28 of 28)