ADTRAN HDSL2 - Manual (Page 70)

HDSL2 Loopback and Control Codes HDSL2 for General Distribution Installation and Maintenance Practice
A-2 61223HDSL2L2-5B
NOTE
In all control code sequences presented, the inband codes are
shown leftmost bit transmitted first, and the ESF data link codes
with rightmost bit transmitted first.
Table A-1. HDSL2 Loopback Control Codes
Type Source * Code Name
Abbreviated (N)
(N)
(C)
(C)
3in7 (1110000)
4in7 (1111000)
5in7 (1111100)
6in7 (1111110)
Loopback data from network toward network in
the H2TU-R
Loopback data from network toward network in
the H2TU-C
Loopback data from customer toward customer
in the H2TU-R
Loopback data from customer toward customer
in the H2TU-C
Wescom (N)
(C)
(N)
(C)
(N)
(N/C)
(N/C)
FF1E
(1111 1111 0001 1110)
3F1E
(0011 1111 0001 1110)
FF02
(1111 1111 0000 0010)
3F02
(0011 1111 0000 0010)
FF48 (ESF-DL)
(1111 1111 0100 1000)
1in3 (100)
FF24 (ESF-DL)
(1111 1111 0010 0100) Loopback data from network toward network at
H2TU-C
Loopback data from customer toward customer
at H2TU-C
Loopback data from network toward network at
H2TU-R
Loopback data from customer toward customer
at H2TU-R
Loopback data from network toward network at
H2TU-R
Loop down everything
Loop down everything
* The Source column indicates from which side of the interface the control codes are sent. For example, an (N)
indicates a network sourced code while a (C) indicates a customer sourced code.
Note: All codes are in-band unless labeled ESF-DL.
Note: All codes listed above must be sent for a minimum of 5 seconds in order for them to be detected and acted
upon.