ADC Campus-RS Remote - Manual (Page 32)

Loopback Operation 152-402-145-02, Issue 2
26 June 16, 2000 H2TU-R-402
Special Loopback Commands
In addition to the GNLB loopback command mode, a HiGain HDSL2 system can be configured for one of three
special loopback command modes. These command modes, A2LB, A3LB, and A4LB, are selected from the ADC
Options maintenance terminal screen or by using the MODE and SEL buttons on the H2TU-C front panel. Once
a loopback mode is activated, other loopback commands can be sent by a test set connected to the craft port on
the H2TU-C or H2TU-R front panel.
A2LB through A4LB are special, addressable, repeater loopback modes that are supported by the H2TU-R-402
(see
Table 11 on page 28 and Table 12 on page 30 for list of Addressable Repeater Loopback Commands). These
loopback modes provide the HiGain HDSL2 system with sophisticated maintenance and troubleshooting tools.
A2LB is patterned after the Teltrend addressable T1 repeater loopbacks. A3LB and A4LB are patterned after the
Wescom addressable T1 repeater loopbacks.
These addressable repeater loopback modes have been enhanced to handle the specific requirements of the
following HiGain HDSL2 customers:
• A2LB (Teltrend) = Southwestern Bell
• A3LB (Wescom) = New England Telephone, Bell Atlantic
• A4LB (Wescom Mod 1) = New York Telephone
A2LB can be configured to do one of the following:
• Block the arming code (after 2 seconds) from exiting the H2TU-C into the network, and replace it with the
AIS code.
• Unblock the AIS code by executing the Far End Activate code.
A3LB differs from A4LB in that A3LB supports the additional (1-in-6) SMJK loopback command.
L
OOPBACK
T
EST
P
ROCEDURES
The following sections provide step-by-step test procedures for verifying the integrity of the HDSL2 channels at
every module location as well as the DS1 channels to the customer and the local DSX-1 interface.
GNLB Test Procedures
Figure 22 on page 27 is a graphical representation of the various loopback configurations with the associated
GNLB commands shown. Also, refer to Table 10 on page 25 for a description of these commands.
To perform the GNLB loopback test procedure:
1 Have the CO tester send the NREM (3-in-7) inband loopup code for 5 seconds. The LBK LED on the front
panel should be a steady yellow, and the loopback mode should be identified on the Monitor screen.
2 Have the CO tester transmit a DS1 test signal towards the H2TU-R-402 and verify that the returned (looped)
signal to the test set is error-free.
3 If step 2 fails, have the CO tester transmit the 3-in-5 inband loopdown code.
4 Have the CO tester send the NLOC (4-in-7) inband loopup for 5 seconds. You should be able to observe the
NLOC message on the Monitor screen.
SMJK loopback commands are only activated by inband commands.