Figure 5-67. Digital Line/Network Loopback; Figure 5-68. Codec Loopback; Codec Line/Net; Csu Loopback - ADTRAN MX2820 System Manual

MX2820 System Manual

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
STS-1 mapper and the T1/E1 LIU. See

CSU Loopback

A CSU Loopback enables the MX2820 STS-1 to generate a CSU loop-up pattern (00001...)
towards the T1 CSU attached to the selected T1 line for 6 seconds. After 6 seconds have
elapsed, the pattern will cease and incoming network traffic will be passed through to the CSU
device. If the CSU device responded to the CSU loop-up pattern, it will return all data back
towards the network. A loop-down pattern (001001....) will be generated towards the CSU for 6
seconds when Data Mode is selected.
When in CSU Loopback, only the Data Mode for the T1 under test
can be selected. Selecting any other option will result in an error
message being displayed.
5-98
STS-1
STS-1
MAPPER
LIU

Figure 5-67. Digital Line/Network Loopback

Figure 5-68
STS-1
STS-1
MAPPER
LIU

Figure 5-68. Codec Loopback

CODEC
(1 of 28)
CODEC
(28 of 28)
for an illustration of this test.
CODEC
(1 of 28)
CODEC
(28 of 28)
NOTE
T1/E1 LIU
(1 of 28)
T1/E1 LIU
(28 of 28)
T1/E1 LIU
(1 of 28)
T1/E1 LIU
(28 of 28)
61186003L1-1D