Loopback Operation - ADC HiGain HLU-200 User Manual

Loopback Operation

The HiGain system has a family of loopback options. The most important of these is the SmartJack loopback
which enables the HRU-412 to respond to the standard (2/3-in-5) SmartJack inband loopback codes and thus
emulate the functions of a standard Network Interface Device (NID). This option can be enabled or disabled
from the terminal SYSTEM SETTINGS MENU (Figure 12).
In addition to the SmartJack loopback, the HiGain system can be configured for one of five special inband
loopback (SPLB) command sequences. These are selected from the SPLB user option shown in Table 10 and
Figure 12. The non-Doubler loopback locations are shown in Figure 7.
GNLB is the HiGain system Generic loopback code. The GNLB allows inband codes issued to the HLU to
loop-up either the HLU/NLOC (4-in-7) or HRU/NREM ( 3-in-7 ) towards the CBA. In addition, it allows inband
codes issued to the HRU to loop-up the HLU/CREM ( 6-in-7 ) or HRU/CLOC (5-in-7) towards the CI. Either
loop-up condition is terminated (looped-down) with the 3-in-5 loop-down code. Both inband codes must be
present for 5 seconds before the HiGain system responds. Table 11 lists the test procedures that apply when
using the GNLB mode.
The A1LB loopback selection, Table 12, complies with that proposed for HDSL systems in the T1E1.4/92
recommendation with the following additions:
•
Query loopback
•
IOR (Intelligent Office Repeater) power-down
•
Three loopback time-out choices
•
Initiation from either end
•
Repeating bit error signatures
•
Alternate query loopback
These additions make A1LB identical to A2LB described below. It is given a separate identity to allow future
T1/E1 enhancements to be added without affecting A2LB.
A2LB through A5LB are four special addressable repeater inband loopback functions which are supported by
the HLU-200 HiGain system. These loopbacks provide the HiGain system with sophisticated maintenance and
trouble shooting tools. Tables 13 through 16 list the details of these SPLB functions. A2LB and A5LB are
patterned after the Teltrend addressable T1 repeater loopbacks. A3LB and A4LB are patterned after the
Wescom addressable T1 repeater loopbacks. All four SPLBs have been enhanced to handle the specific
requirements of the following HiGain system customers:
•
A2LB (Teltrend) = Southwestern Bell
•
A3LB (Wescom) = New England Telephone
•
A4LB (Wescom Mod 1) = New York Telephone
•
A5LB (Teltrend Mod 1) = Southern New England Telephone (SNET)
A5LB differs from A2LB in that A5LB does not block the arming code from exiting the HLU-200 List 1D
toward the CBA. A2LB can be configured to either block this arming code after two seconds, and replace it
with the AIS code, or to unblock it by executing the FAR-END ACTIVATE code. Since A5LB never blocks
the arming code from exiting the HLU-200 List 1D, it does not support this FAR-END ACTIVATE code.
A3LB differs from A4LB in that A3LB supports the additional (1-in-6) SmartJack loopback command.
24 November 22, 1996
150-200-114-03, Issue 03
HLU-200 List 1D