A-1
Section 61222004L2-5, Issue 1
61222004L2-5A
HDSL2 MAINTENANCE MODES
This appendix describes operation of the HDSL2
system with regard to detection of in-band and ESF
facility data link loopback codes. The operation of
the loopback commands in the ADTRAN HDSL2
system is compliant with the recommendation to
ANSI recorded in T1E1.4/92. The HDSL2 network
loopback points described below are shown in
Figures A-1
and
A-2
.
H2TU-C Loopback:
A regenerative loopback of the
DSX-1 signal toward the network.
Appendix A
HDSL2 Loopbacks
H2TU-R Loopback:
A regenerative loopback of the
DS1 signal toward the network. This loopback is in
addition to a separate Smartjack loopback. Separate
activation sequences are provided for the H2TU-R and
the Smartjack loopback initiation.
Upon deactivation of a loopback, the HDSL2 system
will synchronize automatically.
Figure A-2. HDSL2 Element State Diagram
Figure A-1. HDSL2 Loopback Points
LOOPUP / TIMEOUT
STATE
ARMED
STATE
LOOPUP / NO TIMEOUT
STATE
DISARMED
STATE
ACTIVATION
LOOPUP
TIMEOUT
ARMING
TIMEOUT
DEACTIVATION
DISARM
LOOPUP
TIMEOUT
DISABLE
H2TU-C
H2TU-R
DSX-1
Interface
HDSL2
Loop
DS1
Interface
NIU
