
Troubleshooting
150-231-184-05, Revision 05
42
October 25, 1999
HLU-231 List 8D
Table 13.
Summary of HiGain Loopback Codes
Method of Transmission
Loopback
Code
Description
Test Set
Craft Port
MODE/SEL
ARM
11000. . .
2-in-5
NI LPBK
X
SMJK LpUp
(PL)
11000
2-in-5
SmartJack Loopup or NID payload (PL) code. Invokes
HRU loopback towards network.
X
SMJK LpUp
(ESF-DL)
1111-1111-
0100-1000
SmartJack Loopup or NID (ESF-DL) code. Invokes HRU
loopback towards network.
X
DISARM
11100. . .
3-in-5
IR LPDN
X
SMJK LpDn
(PL)
11100
3-in-5
SmartJack Loopdown or NID payload (PL) code. Removes
SMJK, NLOC, NREM, CREM, CLOC, CDUx, and NDUx.
X
SMJK LpDn
(ESF-DL)
1111-1111-
0010-0100
SmartJack Loopdown or NID (ESF-DL) code. Removes
SMJK, NLOC, NREM, CREM, CLOC, CDUx, and NDUx.
X
NLOC and
CREM
D3D3
IOR LPBK (231 ± 2 bit errors)
X
X
X
NDU1 and
CDU1
C741
ILR-1 LPBK (10 bit errors)
X
X
X
NDU2 and
CDU2
C754
ILR-20 LPBK (200 bit errors)
X
X
X
NDU3 and
CDU3
C743
ILR-3 LPBK (30 bit errors)
X
X
X
NDU4 and
CDU4
C744
ILR-4 LPBK (40 bit errors)
X
X
X
NREM and
CLOC
C742
ILR-2 LPBK (20 bit errors)
X
X
X
HiGain systems feature the SmartJack option, which can emulate a Network Interface Device
(NID) for the purpose of loopback testing of the HiGain circuit. SMJK and NREM loopbacks
perform the same functions but their initiation differs. SMJK indicates that the loopback was
initiated by the 2-in-5 inband command. NREM, on the other hand, is initiated by the 3-in-7
inband command or by a command issued from the maintenance terminal or the MODE and SEL
buttons.
Use the inband commands to enable or disable the SMJK loopback options. The HLU-231
system setting is normally enabled to recognize all inband SmartJack loopback commands.