Appendix Ahdsl4 Loopbacks - ADTRAN 220 HDSL4 Installation And Maintenance Practice

HDSL4 MAINTENANCE MODES
This appendix describes operation of the HDSL4
system with regard to detection of in-band and ESF
facility data link loopback codes.
Upon deactivation of a loopback, the HDSL4 system
will synchronize automatically.
Loopback Process Description
In general, the loopback process for the HDSL4
system elements is modeled on the corresponding
DS1 system process. Specifically, the H4TU-C
loopback is similar to an Intelligent Office Repeater
loopback and the H4TU-R loopbacks are similar to an
inline T1 Repeater loopback.
The unit can detect the loopback activation or
deactivation code sequence only if an error rate of
1E -03 or better is present.
61222401L1-5C
Appendix A
HDSL4 Loopbacks
Loopback Control Codes
A summary of control sequences is given in
Table A-1 and Table A-2.
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.
NOTE
A-1