Testing
152-388-115-03, Issue 03
46
April 21, 2000
H2TU-C-388 List 1E
L
OOPBACK
O
PERATION
HiGain HDSL2 has a family of loopback options for analyzing circuit functionality. The loopback signal is
transmitted and returned to the sending device for comparison. This allows you to verify the integrity of the
HDSL2 channels to the H2TU-C, the H2TU-C DSX-1 interface and the DS1 channels to the customer. Loopback
options include:
•
Generic Loopback (GNLB), including the SmartJack (SMJK) option, as described in
•
Special Loopback (SPLB) options, as described in
“Special Loopback Commands” on page 48
and the
following command tables:
–
Addressable Repeater Loopback commands: A2LB, as described in
–
Addressable Repeater Loopback commands: A3LB, A4LB, as described in
Loopback commands can be initiated by:
•
Selecting the loopback type using the MODE and SEL buttons on the H2TU-C front panel or the Manual
Loopback button on the H2TU-R
•
Selecting the loopback type from the Monitor Menu when connected to the craft port of the H2TU-C or
H2TU-R
•
Entering the loopback code into the test equipment connected to the H2TU-C or H2TU-R
Generic Loopback Commands
The HiGain HDSL2 Generic Loopback (GNLB) commands allow you to use inband codes to loop up either
NLOC (4-in-7) or NREM (3-in-7) toward the network. In addition, these inband codes loop up CREM (6-in-7) or
CLOC (5-in-7) toward the customer. Either loopup condition can be terminated (looped down) with the 3-in-5,
SMJK loop-down code. All inband codes must be present for at least 5 seconds before the HiGain HDSL2 system
responds. TLOS is a logic loopback caused by loss of the DS1 input from the CI.
summarizes the available loopbacks in the system, and
summarizes the HiGain
HDSL2 generic loopback commands.
“GNLB Test Procedures” on page 50
details the test procedures when using
the GNLB mode.
Figure 24.
Loopback Summary
HiGain HDSL2 only supports one active loopback, however, SmartJack loopback can be present
along with one other network loopback.
Network
Customer
Premises
Activate loopback using
one of the following:
• Maintenance Terminal
• Test Set
• MODE/SEL pushbuttons
Activate loopback using
one of the following:
• Test Set
• LBK pushbutton
• Maintenance Terminal
H2TU-C
H2TU-R
NLOC
NREM
SMJK
TLOS
CREM
CLOC
Содержание H2TU-C-388 HiGain
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