A-3
Section 61246045L1-5, Issue 2
61246045L1-5B
The unit can detect the loopback activation or
deactivation code sequence
only
if an error rate of
1E
-03
or better is present.
NOTE:
In all control code sequences presented, the
in-band codes are shown leftmost bit
transmitted first, and the ESF data link
codes with rightmost bit transmitted first.
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
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 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.
Table A-1. HDSL Standard Loopback Control Codes
Name
Arming (In-band) ...............................
Arming (ESF) .....................................
Activation (HTU-C) ..........................
Activation (HRE #1) ..........................
Activation (HRE #2) ..........................
Activation (HTU-R) ...........................
Deactivation (all HDSL elements) ....
Disarming (In-band) ..........................
Disarming (ESF) ................................
Arming Timeout .................................
Loop-up Timeout ...............................
Detection Time
5 Seconds
4 Repetitions
> 4 Seconds
> 4 Seconds
> 4 Seconds
> 4 Seconds
>5 Seconds
5 Seconds
4 Repetitions
2 Hours
Programmable from HTU-C:
None, 20, 60, or 120 minutes
Code
11000 ...............................
0001 0010 1111 1111 .....
1101 0011 1101 0011 .....
1100 0111 0100 0001 .....
1100 0111 0101 0100
1100 0111 0100 0010 .....
1001 0011 1001 0011 .....
11100 ...............................
0010 0100 1111 1111 .....
N/A ..................................
N/A ..................................
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.
