Table A-1. Hdsl Standard Loopback Control Codes - ADTRAN T200 Installation And Maintenance Manual

Disarmed State
The disarmed state is the normal mode of operation.
Each HDSL element is transparent to the data flow.
However, the in-band data flow and the ESF data link
are monitored for the arming sequence.
The in-band control code sequence used to
simultaneously arm the loopback capability of all
HDSL elements is the standard 5-bit in-band sequence
used for NIU Smartjack loop-up. Each HDSL
element arms after receiving the following code for
five seconds:
ARM SEQUENCE
11000 for five seconds
The arming process ensures unambiguous race-free
operation of HDSL element arming and Smartjack
loop-up. The HDSL unit can detect the sequence
without interfering with the detection by the
Smartjack. Presently, the Smartjack loop-up response
requires a duration of at least five seconds. The
objective of the HDSL detection scheme is to arm the
HDSL elements without interfering with the
Smartjack loop-up.
The requirement imposed on the arm sequence is that
the Smartjack should loop-up and all HDSL elements
Name
Arming (In-band)
Arming (ESF)
Activation
(HTU-C)
Activation
(HDSL Range Extender)
Activation
(HTU-R)
Deactivation
(all HDSL elements)
Disarming (In-band)
Disarming (ESF)
Arming Timeout
Loop-up Timeout
61246041L3-5A

Table A-1. HDSL Standard Loopback Control Codes

Code
11000
5 Seconds
0001 0010 1111 1111
4 Repetitions
1101 0011 1101 0011
> 4 Seconds
> 4 Seconds
1100 0111 0100 0001
1100 0111 0100 0010
> 4 Seconds
1001 0011 1001 0011
> 5 Seconds
11100
5 Seconds
0010 0100 1111 1111
4 Repetitions
N/A
2 Hours
N/A
Programmable from
HTU-C:
None, 20, 60,
or 120 minutes
61246041L3-5, Issue 1
make a transition from the disarmed state into the
armed state. All other control code sequences are
ignored in the disarmed state.
The ESF data link sequence used to simultaneously
arm the loopback capability of all HDSL elements is
the standard 16-bit ESF data link sequence used for
NIU Smartjack loop-up.
Race-free operations of the HDSL element arming and
Smartjack loop-up is accomplished as described for
the in-band code. For example, the ESF arm sequence
causes the Smartjack to loop-up and all of the HDSL
elements to move from the disarmed state into the
armed state. All other ESF data link control code
sequences are ignored in the disarmed sate.
Armed State
In the armed state, the HDSL system element
continues to be transparent to data flow. However, the
in-band data flow is monitored for the activation and
disarming sequences. The ESF data link is monitored
for the disarming sequence.
Detection Time Comments
Signal sent in-band or over ESF data link.
HDSL elements in disarmed state make
transition to armed state. Detection of either
code results in Smartjack loop-up, if NIU
loopback is enabled.
Signal sent in-band. HDSL elements in armed
state make transition to loop-up state.
Loop-up state timeout is programmable from
the HTU-C.
Signal sent in-band. HDSL element in loop-up
state makes transition to armed state.
Signal sent in-band or over ESF data link.
HDSL elements in any state make transition.
HDSL elements in armed state make transition
to disarmed state.
HDSL element in loop-up makes transition to
armed state.
ESF ARM SEQUENCE
0001 0010 1111 1111
for four repetitions
A-3