Codec Line/Net; Remote Loopback; Csu Loopback; Csu Loopback W/Bert - ADTRAN MX2800 M13 User Manual

Section 6, Loopbacks

Codec Line/Net

A Codec 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 codec. Both the network and the local loop side of the
loopback are executed at the edge of the codec, completely testing the M13 mux and the T1/E1 LIU. See
Figure 6-6 on page 6-4 for an illustration of this test.
DSX-3 DSX-3
LIU LIU

Remote Loopback

A Remote Loopback performs a loopback of the selected T1/E1 on the far-end M13 multiplexer. If an
MX2800 is located at the far end, an Analog Network Loopback is executed when a Remote Loopback is
engaged. This loopback is only available when the DS3 is configured for C-bit parity framing since it
requires the availability of the far-end alarm and control (FEAC) channel. See ANSI T1.107.

CSU Loopback

A CSU Loopback enables the MX2800 to generate a CSU loop up pattern (001001...) toward the T1 CSU
attached to the selected T1 line for six seconds. After six seconds have elapsed, the pattern ceases; and
incoming network traffic is passed through to the CSU device. If the CSU device responded to the CSU
loop up pattern, it returns all data back toward the network. A loop down pattern (0000100001....) is
generated toward the CSU for 6 seconds when Data Mode is selected.
When in
selected. Selecting any other option will result in an error message.

CSU Loopback w/BERT

A CSU Loopback w/BERT enables the MX2800 to test the local T1 loop to the CSU using the QRSS
pseudorandom bit sequence. When
loopback toward the CSU attached to the selected T1 line. Six seconds after starting the CSU loop up
pattern, the MX2800 ceases sending the CSU loop up pattern and begins sending an unframed QRSS
pattern toward the CSU. If the CSU device responded to the CSU loop up pattern, the MX2800 checks the
incoming pattern for errors. Additional menu items appear to show the state of pattern synchronization,
6-4
F F
R R
D D
A A
S S
F F
M M
2 2
R R
E E
M23 M23
D D
A A
R R
S S
M M
MUX/DMUX MUX/DMUX
3 3
E E
R R

Figure 6-6. Codec Loopback

, only the
CSU Loopback
CSU Loopback w/BERT
MX2800 M13 Multiplexer User Manual
CODEC CODEC
(1 of 28) (1 of 28)
M12/G.747 M12/G.747
MUX/DMUX MUX/DMUX
(1 of 7) (1 of 7)
CODEC CODEC
(28 of 28) (28 of 28)
NOTE
for the T1 under test may be
Data Mode
is selected, the MX2800 initiates a CSU
T1/E1 LIU T1/E1 LIU
(1 of 28) (1 of 28)
T1/E1 LIU T1/E1 LIU
(28 of 28) (28 of 28)
61200290L1-1G