Table A-2. In-Band Addressable Loopback Codes - ADTRAN HDSL DDM+ HTU-C Installation And Maintenance Practice

Table A-2. In-band Addressable Loopback Codes

Function
Arm
Disarm
HTU-C Network
Loop-up
HRE Network
Loop-up
HRE2 Network
Loop-up
Loopdown
61247003L6-5A
Code
11000
(also known as a
2-in-5 pattern)
11100
(also known as a
3-in-5 pattern)
D3D3
1101 0011 1101 0011
C741
1100 0111 0100 0001
C754
1100 0111 0101 0100
9393
1001 0011 1001 0011
Appendix A, HDSL Loopbacks - HDSL Maintenance Modes
The HTU-R will loop up towards the network. No AIS
or errors will be sent as a result of this loopback. The
HTU-C and HRE will arm.
The HTU-C and HRE are removed from the armed
state. If any of the units are in loopback when the
11100 pattern is received, they will loop down. The
LBK LEDs will turn off on all units.
If the units have been armed and no units are in
loopback*, the HTU-C will loopup towards the
network, 2 seconds of AIS (all 1s) will be sent,
5 seconds of data will pass, and 231 bit errors will be
injected into the DSX-1 signal. As long as the pattern
continues to be sent, 231 errors will be injected every
20 seconds. When the pattern is removed, the unit
will remain in loopback. If the pattern is reinstated,
the injection of 231 bit errors will resume at
20-second intervals.
If an HRE is present, the units have been armed, the
HRE will loopup towards the network, 2 seconds of
AIS (all 1s) will be sent, 5 seconds of data will pass,
and 10 bit errors will be injected into the DSX- 1
signal. As long as the pattern continues to be sent,
10 errors will be injected every 20 seconds. When the
pattern is removed, the unit will remain in loopback.
If the pattern is reinstated, the injection of 10 bit
errors will resume at 20-second intervals.
If a second HRE is present, the units have been
armed, the HRE will loop up towards the network,
2 seconds of AIS (all 1s) will be sent, 5 seconds of data
will pass, and 200 bit errors will be injected into the
DSX-1 signal. As long as the pattern continues to be
sent, 200 errors will be injected every 20 seconds.
When the pattern is removed, the unit will remain in
loopback. If the pattern is reinstated, the injection of
200 bit errors will resume at 20-second intervals.
Any HTU-C and HRE units currently in loopback
towards the network will loopdown and will retain the
armed state.
Response
A-3