Troubleshooting
152-319-100-02, Revision 02
44
April 21, 2000
H2TU-C-319 List 1 and List 1C
You can terminate loopbacks manually and exit the MAN LPBK mode by simultaneously pressing the MODE
and SEL buttons for 3 or more seconds. If no loopback is active, the MAN LPBK mode automatically terminates
after 30 seconds.
All loopbacks can be initiated by inband commands in the T1 payload or by a command from the HiGain Solitaire
system (front-panel buttons or maintenance screen selections). Therefore, whenever a loopback is active, the
method by which it was activated is indicated in the Loopback and Status screens by the annotation HG (HiGain
Solitaire) or PL (Payload) adjacent to the identified loopback. For example, NREM-HG indicates that the
loopback was initiated by the HiGain Solitaire system.
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.
General Troubleshooting Tips
If trouble is encountered on the DSX-1 interface of the H2TU-C, verify that the:
•
H2TU-C is making a positive connection with its shelf connector.
•
H2TU-C internal equalizer is set to the correct distance range per
. All equalizers should
be set to the distance from the DSX-1 to the shelf.
The transmit and receive DS1 ports have splitting access jacks and miniature, 210-series, bridging jacks as shown
in
. Connecting one cable between the two bridging jacks and another between the two LINE
jacks splits the IN and OUT and creates metallic loopbacks towards both the DSX-1 and the H2TU-C-319. If
separate plugs are inserted into both LINE jacks with the other end disconnected, the BRG jacks can be used to
send and receive test patterns towards the DSX-1.
GNLB Test Procedures
is a graphical representation of the various loopback configurations with the associated
GNLB commands shown. Also, refer to
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. You should observe the
NREM message on the front-panel display. (The Status LED on the front panel should be green, and the
loopback mode should also be identified on the Span Status screen.)
2
Have the CO tester transmit a DS1 test signal towards the H2TU-C 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 observe the NLOC
message on the front-panel display. (The Status LED on the front panel should be yellow, and the loopback
mode should also be identified on the Span Status screen.)
5
Repeat Step 2. If the test passes, the problem is in the downstream direction. If it fails, the problem is in the
upstream direction.
SMJK loopback commands are only activated by inband commands.
