Section 311-610-20B
030-101522 Rev. C
7
0509IBRC
4.6
Manual Loopback
The NIU loopback state can be controlled by pressing the front-
panel MAN LB push button. Depression of the MAN LB push
button will cycle through the loopback states.
If depressed for 3 to 5 seconds, the LB LED will be on solid
(yellow). If released in this interval, the Network Loopback
will be activated.
If depressed for greater than 5 seconds, the LB LED will be-
gin blinking (yellow) at approximately 1 time per second. If
released after 5 seconds, the Dual Loopback will be acti-
vated.
When first depressed, the LB LED will go off and remain
off during the first 3 seconds that the MAN LB is depressed.
If released during this 3 second period, all existing loopback
conditions will be deactivated.
4.7
Loopback Time-out
4.7.1
The 3116-10 provides a selectable loopback time-out
feature that can be configured to release a code-activated loop-
back condition either 20, 60, or 120 minutes or 24 hours after
initial activation.
4.7.2
The loopback condition can be released before the
timeout expiration period by: 1) sending loop-down code to the
NIU from the network test location, 2) through the craft inter-
face port, or 3) by pressing the front-panel MAN LB switch for
less than 3 seconds. Loopback timeout can be permanently dis-
abled via an option provisioned locally from the craft interface
port or remotely from the network test location.
4.8
CPE (Dual) Loopback Activation
4.8.1
To activate CPE loopback, the unit must first be in net-
work-side loopback from the remote test location. At this point,
re-application of loop-up code will operate CPE loopback allow-
ing the customer or craft personnel to evaluate the integrity of
the circuitry on the CPE-side of the demarcation point. The unit
can be placed in CPE loopback via the front-panel MAN LB
push button (see Paragraph 4.6). CPE Loopback can also be ac-
tivated and deactivated from the Circuit Status Menu via the
craft interface port.
4.8.2
When CPE loopback is activated, it will remain acti-
vated until:
1.
the NIU detects a loop-down command from the Network-
side,
2.
when the timeout release feature expires,
3.
when released via the craft interface port, or
4.
when the MAN LB switch is pressed.
5.
SECTIONALIZATION ALARM FEATURES
The NIU
is equipped with features that allow a network moni-
toring location to differentiate between fault conditions that are
beyond the NIU (i.e., CPE or inside wiring) and those that are
legitimate network problems.
5.1
CPE LOS Modes
5.1.1
LB Upon CPE LOS
In this mode, the unit continuously monitors the DS1 signal
from the CPE for customer loss of signal, and upon detecting a
loss will change the CPE LED to red and cause the unit to enter
Loopback toward the network. When the signal from the CPE
is restored the unit will return to normal operation. LB upon
CPE LOS is an option that can be set remotely via TL1 or 16-bit
commands or locally via the craft interface port. When set to en-
ter loopback upon detecting a loss of signal from the CPE, the
NIU will assume the transmission path as shown in Figure 6.
5.1.2
AIS Upon CPE LOS
In this mode, the unit continuously monitors the DS1 signal
from the CPE for customer loss of signal, and upon detecting a
loss will change the CPE LED to red and send an unframed, all-
ones Alarm Indication Signal (AIS) to the network. When the
signal from the CPE is restored the unit will return to normal op-
eration. The AIS upon CPE LOS mode is an option that can be
set remotely via TL1 or 16-bit commands or locally via the craft
interface port.
5.1.3
Idle Code Upon CPE LOS
In this mode, the unit continuously monitors the DS1 signal
from the CPE for customer loss of signal and upon detecting a
loss will change the CPE LED to red and send an Idle code to-
ward the network. When signal from the customer is restored,
the NIU returns to normal operation. The specific format in
which the Idle signal is sent toward the network facility is depen-
dent on the format of the DS1 signal received from the network
facility:
1.
If the received signal is SF, the Idle signal will be SF and will
provide a 0001 0111 repeating pattern in each of the 24 DS0
time slots,
2.
If the received signal is ESF, the Idle signal will be ESF and
provide a 0001 0111 repeating pattern in each of the 24 DS0
time slots. In addition, the ESF Data Link will contain the
ESF yellow alarm signal 1111 1111 0000 0000, interrupted
each second with a 100ms burst of LAPD idle code 0111
1110,
3.
If no signal is received from the network or if the DS1 signal
is unframed, the NIU will default to the SF Idle mode.
The Idle Code upon CPE LOS mode is an option that can be set
remotely or locally via TL1 or 16-bit commands or via the craft
interface port.
5.1.4
AIS-CI Upon CPE LOS
In this mode, the unit continuously monitors the DS1 signal
from the CPE for customer loss of signal, and upon detecting a
loss will change the CPE LED to red and send an AIS-CI pattern
toward the network. When signal from the customer is restored,
the unit returns to normal operation. The AIS-CI upon CPE
LOS mode is an option that can be set remotely via TL1 16-bit
commands or locally via the craft interface port.
5.2
CPE LOS Override
5.2.1
When the NIU detects a loss of signal from the CPE
and if the CPE LOS option is enabled, the NIU will respond in
