Gnlb Test Procedures; Loopback Modes - ADC HiGain H2TU-C-202 User Manual

152-202-115-04, Revision 04

GNLB Test Procedures

Figure 27 is a graphical representation of the various loopback configurations with the associated GNLB
commands shown. Also, refer to
To perform the GNLB loopback test procedure:
1 Have the CO tester send the NREM (3-in-7) inband loopup code for 5 seconds to loop up the H2TU-R. The
loopback mode, NREM, should be identified on the Span Status screen.
2 Have the CO tester transmit a T1 test signal towards the H2TU-C and verify that the signal returned (looped)
from the H2TU-R 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. The LBK LED on the front panel
should be a steady 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.
H2TU-C HLU HLU HLU
H2TU-C HLU HLU HLU
H2TU-C
HLU HLU HLU
H2TU-C
SPAN 4
NLOC
4-in-7
HLU HLU HLU
H2TU-C
CREM
6-in-7
All ones HLU HLU HLU
H2TU-C
HLU HLU HLU HLU HLU HLU HLU HLU HLU HLU HLU HLU HLU HLU HLU
All ones H2TU-C
HLU HLU HLU
All ones
H2TU-C
* Set the NLBP option to AIS to send AIS (indicated by an all ones pattern) for any network loopback.
A3LB and A4LB loopback codes.
‡ A2LB loopback codes.
GNLB loopback codes.
H2TU-C-202 List 1E
Table 21 on page 44
Loopbacks Toward Network
FF04
C741
1 NRG1 U D C
2-in-6
6 i n 4
SPAN 1
110000
0 0 1 1 1 1
H2RU
9 0 - 4 U
FF1E
D3D3 ‡
1111000
3F1E
Loopbacks Toward Customer
D3D3 ‡
1111110
3F04
C741
CRG1
4-in-6
SPAN 1
111100
H2RU
Figure 27. Loopback Modes
for a description of these commands.
HDSL2 SPAN
HDSL2 SPAN
HDSL2 SPAN
FF06
‡ ‡
C754
1 NRG2 U D C
3-in-6
6 i n 4
SPAN 2
SPAN 3
111000
0 0 1 1 1 1
H2RU
D H 9 0 - 4 U D H
HDSL2 SPAN
HDSL2 SPAN
HDSL2 SPAN
3F06
‡ ‡
C754
CRG2
5-in-6
SPAN 2 SPAN 3
111110
H2RU
April 21, 2000
TLOS*
HRU-412 HRU-412
LOGIC All ones
HRU-412
H2TU-R
SMJK*
HRU-412 HRU-412
2-in-5 All ones
11000 HRU-412
H2TU-R
FF02
NREM* NREM
C742 ‡
1110000 3-in-7
HRU-412 HRU-412 HRU-412 HRU-412
HRU-412 HRU-412 3 in 7 All ones
HRU-412
H2TU-R
All ones
H2TU-R
CLOC
HRU-412 HRU-412 H2TU-R
5 IN 7
All ones
HRU-412
H2TU-R
3F02
CLOC CLOC CLOC CLOC
C742 ‡
1111100 5-in-7
HRU-412 HRU-412 HRU-412 HRU-412
5 IN 7 5 IN 7 5 IN 7
HRU-412 HRU-412 HRU-412 H2TU-R
H2TU-R
Testing
47