Special Loopback (Splb) Mode; Gnlb Mode Loopback Commands; A3Lb Mode Loopback Commands - ADC HiGain H2TU-C-202 User Manual

LTPH-UM-1208-01
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PECIAL OOPBACK
The HDSL2 system can be configured from the ADC Options menu for one of two SPLB modes, GNLB or A3LB.
These modes permit the HDSL2 system to respond to the loopback commands described in the following
paragraphs.

GNLB Mode Loopback Commands

The GNLB (Generic Loopback) commands allow the use of inband codes to loop up either NLOC (4-in-7) or
NREM (3-in-7) towards the network. Additionally, these inband codes loop up CREM (6-in-7) or CLOC (5-in-7)
towards the customer. Either loopup condition can be terminated (looped down) with the 3-in-5, SMJK loopdown
code. All inband codes must be present for at least 5 seconds before the HDSL2 system responds. TLOS is a logic
loopback caused by loss of the DS1 input from the CI.
Figure 28 on page 42
HDSL2 generic loopback commands. See
when using the GNLB Special Loopback Mode.
HiGain systems feature the SmartJack option which can emulate a Network Interface Device
(NID) for loopback testing of the HDSL2 circuit. SMJK and NREM loopbacks perform the same
functions, but their initiation differs. SMJK indicates that the loopback was initiated by the 2-in-5
inband command. Conversely, NREM is initiated by the 3-in-7 inband command, or by a
command issued from the maintenance terminal.
Use the inband commands to enable or disable the SMJK loopback options. The HDSL2 system
setting is normally enabled to recognize all inband SmartJack loopback commands.

A3LB Mode Loopback Commands

A3LB loopback commands can be sent by a test set connected to the H2TU-C or H2TU-R. See
page 47 for a list of the commands.
A3LB is a special, addressable, repeater loopback mode which is supported by the H2TU-C. This loopback mode
provides the HDSL2 system with sophisticated maintenance and troubleshooting tools. A3LB is patterned after
the Westell addressable T1 repeater loopbacks.
A3LB supports the additional (1-in-6) SMJK loopback command.
SMJK loopback commands are activated only by inband commands.
H2TU-C-202 List 7G
(SPLB) M
summarizes the available loopbacks in the system, and
"GNLB Test Procedures" on page 45
ODE
June 6, 2003
Table 24 on page 45 summarizes the
for the test procedures that apply
Table 25 on
Testing
43