A-3
Section 61246026L6-5, Issue 2
61246026L6-5B
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.
ESF Arm Sequence
0001 0010 1111 1111
for 4 repetitions
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.
All other in-band and ESF data link control code
sequences are ignored in the armed state. An arming
timeout value causes automatic return to the disarmed
state.
Transition from armed to loop-up state:
An
in-band control code sequence is used to command a
specific HDSL element to move from the armed state
into the loop-up state. Each HDSL element has a
unique 16-bit activation control code sequence as
shown in the following example:
HTU-C Activation Sequence
101 0011 1101 0011
HTU-R Activation Sequence
1100 0111 0100 0010
The designated HDSL element will loop-up after
receiving the proper activation sequence.
Transition from armed to disarmed state:
All
HDSL elements can be commanded to move from the
armed state into the disarmed state by the standard
5-bit in-band disarming sequence used for NIU
Smartjack loop-down. Each HDSL element must
disarm after receiving the following code for five
seconds:
Disarm Sequence
11100
Table A-1. HDSL Standard Loopback Control Codes
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
Detection Time
5 Seconds
4 Repetitions
> 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 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.
