ADTRAN 4200659L1 - Manual (Page 126)

Chapter 6. Diagnostics
6-4 MX2800 STS-1 User Manual 61200659L1-1
Digital Line/Net
A D IGITAL L INE /N ET 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 deep into the LIU through the receiver, receive equalizer,
transmit jitter attenuator, and finally, through the T1/E1 transmit
drivers. See Figure 6-5 for an illustration of this test.
Figure 6-5. Digital Line/Network Loopback
Codec Line/Net
A C ODEC L INE /N ET 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
Figure 6-6 for an illustration of this test.
Figure 6-6. Codec Loopback
STS-1
MAPPER
T1/E1 LIU
(1 of 28)
T1/E1 LIU
(28 of 28)
STS-1
LIU
CODEC
(1 of 28)
CODEC
(28 of 28)
STS-1
MAPPER
T1/E1 LIU
(1 of 28)
T1/E1 LIU
(28 of 28)
STS-1
LIU
CODEC
(1 of 28)
CODEC
(28 of 28)