Table 7. Loopback Types - ADTRAN Total Access SHDSL LTU Installation And Maintenance Practice

Loopbacks
There are five types of local loopbacks and five types of
remote loopbacks available for each of the two line
interfaces (G.703, and SHDSL). When initiating a
loopback, the first step is choosing a line interface.
When G.703 is chosen, the loopback will occur at the
G.703 drivers and receivers. When SHDSL is chosen,
the loopback will occur at the SHDSL drivers and
receivers. The loopback descriptions and illustrations
are shown in Table 7.
Loopback Type
Local Dual Sided
Loopback
Remote Dual Sided
Loopback
Local Network
Transparent
Loopback
Remote Network
Transparent
Loopback
Local Network
Nontransparent
Loopback
Remote Network
Nontransparent
Loopback
Local Customer
Transparent
Loopback
61182118L1-5B

Table 7. Loopback Types

Description
Provides a bidirectional loopback at the LTU.
Initiated at the LTU and provides bidirectional
loopback at the NTU.
Provides a loopback at the LTU in the network
direction. Data is passed transparently to the
customer side.
Initiated at the LTU and provides a loopback at
the NTU in the network direction. Data is
passed transparently to the customer side.
Provides a loopback at the LTU in the network
direction. AIS signal is injected into the
customer side.
Initiated at the LTU and provides a loopback at
the NTU in the network direction. AIS signal is
injected into the customer side.
Provides a loopback at the LTU in the
customer direction. Data is passed
transparently to the network side.
Issue 2, July 2004
NOTE
All remote loopbacks are initiated at the local
2W/4W SHDSL LTU unit.
Illustration
LTU
LTU
LTU
LTU
LTU
LTU
LTU
TX Data
NTU
NTU
NTU
TX Data
NTU
TX Data
NTU
TX AIS
NTU
TX AIS
NTU
11