A-3
Section 61246001L2-5, Issue 2
61246001L2-5B
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 of
the HDSL elements is the following 5-bit pattern:
Arm Sequence ................................. 11000
Note that this sequence is the standard NIU loop-up
code. If the NIU loopback feature for the HDSL
circuit is enabled (see
HTU-C Switch Options
), the
arming sequence will activate the NIU loopback in the
HTU-R. If the NIU loopback feature is disabled and
an external Smartjack NIU is present, the HDSL
arming process will not interfere with NIU detection
of the loop-up code.
All other in-band sequences are ignored in the
disarmed state.
The ESF Data Link sequence used to simultaneously
arm the loopback capability of all of the HDSL
elements is the following 16-bit pattern ESF data link
sequence:
ESF Arm Sequence ......................... 0001 0010 1111 1111
for four repetitions
HDSL element arming and NIU loop-up is performed
as described for the in-band arming sequence.
All other ESF patterns are ignored in the disarmed
state.
In the
Armed State
, the HDSL system element
continues to be transparent to the data flow. However
the in-band data flow and ESF data link is monitored
for disarming and activation codes. An arming time-
out value causes the automatic return of the HDSL
element 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 .......... 1101 0011 1101 0011
HTU-R Activation Sequence .......... 1100 0111 0100 0010
HRE Activation Sequence .............. 1100 0111 0100 0001
The designated HDSL element will loop-up after
receiving the proper activation sequence.
If the NIU loopback feature for the HDSL circuit is
enabled (see
HTU-C Switch Options
), the 5-bit in-
band arming sequence (11000) or the 16-bit ESF data
link sequence (0001 0010 1111 1111) will activate the
NIU loopback in the HTU-R.
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 per element:
Disarm Sequence ............................. 11100
The disarming process ensures race-free operation of
HDSL element disarming and Smartjack loop-down.
Duration of the disarm sequence may need to exceed
24 seconds to allow detection and loop-down of up to
three HDSL elements and the Smartjack.
All HDSL elements can be commanded to move from
the armed state into the disarmed state by the ESF
DATA LINK disarming sequence used for NIU
Smartjack loop-down as follows:
ESF Disarm Sequence ..................... 0010 0100 1111 1111
for four repetitions per
element in loopback
The disarming process ensures race-free operation of
HDSL element disarming and Smartjack loop-down.
Duration of the disarm sequence may need to exceed
16 repetitions to allow detection and loop-down of up
to three HDSL elements and the Smartjack. This
sequence will loop-down the Smartjack and the HDSL
element.
All HDSL elements will automatically move from the
armed state into the disarmed state when a default
timeout value of two hours is reached.
Arming Time-Out ............................ 2 Hours
In the
Loop-up State
, the selected HDSL element
provides continuous loop-up of the DS1 signal.
However, the data flow is monitored for the in-band
deactivation sequence, the in-band disarming
sequence, and the ESF data link disarming sequence.
Also, a loop-up timeout value causes automatic return
to the armed state. All other control code sequences
are ignored in the loop-up state.
