Appendix Ahdsl Loopbacks; Table A-1. Hdsl Loopback Control Codes - ADTRAN AHT1U Installation & Maintenance

HDSL MAINTENANCE MODES
This appendix describes operation of the HDSL system
with regard to detection of in-band and ESF facility data
link loopback codes.
Upon deactivation of a loopback, the HDSL system will
synchronize automatically. Note that the synchronization
process of the HDSL system upon deactivation of the
HRE loopback could take up to 15 seconds, ensuring all
system elements are synchronized.
Loopback Process Description
In general, the loopback process for the HDSL system
elements is modeled on the corresponding DS1 system
process. Specifically, the HTU-C loopback is similar to an
Intelligent Office Repeater loopback and the HTU-R
loopbacks are similar to an inline T1 Repeater loopback.
In-band control code sequences are transmitted over the
DS1 link by either the unframed or overwrite method.
The HDSL elements respond to either method.
The unframed method produces periodic control
sequences and the normal DS1 framing bit is omitted.
The overwrite method produces periodic control
sequences. However, once per frame, the framing bit
overwrites one of the bits in the control sequence.
Type Source
Abbreviated (N) ................... 3in7 (1110000) .................. Loopback data from network toward network in the HTU-R.
(N) ................... 4in7 (1111000) .................. Loopback data from network toward network in the HTU-C.
(N) ................... 2in6 (110000) .................... Loopback data from network toward network in first HRE.
(N) ................... 3in6 (111000) .................... Loopback data from network toward network in second HRE.
(C) .................... 6in7 (1111110) .................. Loopback data from customer toward customer in HTU-C.
(C) .................... 5in7 (1111100) .................. Loopback data from customer toward customer in HTU-R.
(C) .................... 4in6 (111100) .................... Loopback data from customer toward customer in first HRE.
(C) .................... 5in6 (111110) .................... Loopback data from customer toward customer in second HRE.
Wescom (N) ................... FF1E .................................. Loopback data from network toward network at HTU-C.
(C) .................... 3F1E .................................. Loopback data from customer toward customer at HTU-C.
(N) ................... FF04 .................................. Loopback data from network toward network at HRE1.
(N) ................... FF06 .................................. Loopback data from network toward network at HRE2.
(C) .................... 3F04 ................................... Loopback data from customer toward customer at HRE1.
(C) .................... 3F06 ................................... Loopback data from customer toward customer at HRE2.
(N) ................... FF02 .................................. Loopback data from network toward network at HTU-R.
(C) .................... 3F02 ................................... Loopback data from customer toward customer at HTU-R.
(C) .................... FF48 (ESF-DL) ................. Loopback data from customer toward customer at HTU-R.
(N) ................... 1in6 (100000) .................... Loopback data from network toward network at HTU-R.
(N) ................... FF48 (ESF-DL) ................. Loopback data from network toward network at HTU-R.
(N/C) ............... 1in3 (100) .......................... Loopdown everything.
(N/C) ............... FF24 (ESF-DL) ................. Loopdown everything.
Notes: The Source column indicates which side of the interface the control codes are sent from. For example, an (N) indicates a network
sourced code while a (C) indicates a customer sourced code.
All codes are inband unless labeled ESF-DL
All codes listed above must be sent for a minimum of 5 seconds in order for them to be detected and acted upon.
61245002L6-5C
Appendix A
HDSL LOOPBACKS

Table A-1. HDSL Loopback Control Codes

Code Name
Section 61245002L6-5, Issue 3
The unit can detect the loopback activation or deactivation
code sequence only if an error rate of 1E
present.
DDS Latching Loopback Operation
If the unit is optioned for FT1 mode, then DDS Latching
Loopback operation is supported as described in Bellcore
TA-TSY-000077, Issue 3, Section 5.1.3. The HTU-C and
any HRE units which are in the HDSL circuit are treated
as Identical Tandem Dataports and the HTU-R is treated
as a Different Tandem Dataport. The HTU-R will
establish a network loopback upon detection of standard
DDS NI-NEI/RPTR loopback sequence. When using
HRE(s) in the circuit, each HRE will respond as a down
stream DS0 DP tandem element and provide a network
loopack.
Loopback Control Codes
A summary of control sequences is given in Tables A-1
and A-2.
NOTE
In all control code sequences presented, the
in-band codes are shown left-most bit transmitted
first, and the ESF data link codes with right-most
bit transmitted first.
-03 or better is
A-1