Section 311-580-20B
030-101527 Rev. B
8
0407IBRB
enter loopback upon loss of signal from the CPE
send AIS to the network upon loss of signal
send Idle to the network upon loss of signal
send AIS-CI to the network upon loss of signal
5.2.2
No matter what action the NIU takes upon detecting
a loss of signal from the CPE, that mode can be remotely over-
ridden by sending a loop-down command to the NIU. Hence,
CPE LOS Override.
5.2.3
Upon detecting the loop-down command, the NIU will
disable the CPE LOS function and operate as if the CPE LOS
function is actually set for disable. During this mode, the NIU
will respond to normal loop-up and loop-down commands. The
CPE LOS Override feature will time out in 20 minutes. At the
end of 20 minutes, the NIU will re-enable the CPE LOS function
and respond accordingly. That is, if a loss-of-signal condition
from the CPE still exists, the NIU will, again, respond according
to how the CPE LOS option is set (LB/AIS/Idle/AIS-CI).
5.3
RAI-CI and AIS-CI Alarms
In this mode, the unit continuously monitors both the signal
from the customer and from the network facility in order to de-
termine what type of alarm signal to send back toward the
network monitoring location. This capability, along with the
uniquely-identifiable Remote Alarm Indication - Customer In-
terface (RAI-CI) and Alarm Indication Signal - Customer
Interface (AIS-CI) signals, allows test personnel to accurately
sectionalize network facility problems versus CPE problems.
5.3.1
RAI-CI
If the unit sees a Remote Alarm Indication signal coming from
the customer equipment (SF or ESF framed), and does not de-
tect an Alarm Indication Signal (AIS), Loss of Frame (LOF) or
Loss of Signal (LOS) on the network, the unit will send a Remote
Alarm Indication (RAI-CI) toward the network if the network
is ESF.
5.3.2
AIS-CI
5.3.2.1
If the unit sees an Alarm Indication Signal coming
from the customer equipment (AIS-CI), and does not detect a
Loss of Frame (LOF), or Loss of Signal (LOS) on the network,
the unit will send a unique Alarm Indication Signal (AIS-CI) to-
ward the network.
5.3.2.2
Both AIS-CI and RAI-CI are backwards compatible
with existing network devices and will appear as normal AIS or
RAI.
5.3.2.3
Upon detecting a loss of signal on the network side of
the unit, the unit will send an Alarm Indication Signal (AIS) to-
ward the customer equipment. The customer equipment, in
turn, will send a Remote AIarm Indication (RAI) signal back to-
wards the network.
6.
PERFORMANCE MONITORING
/
REPORTING
The unit continuously monitors the DS1 bit stream in both the
Network-to-CPE (A-Z) and CPE-to-Network (Z-A) direction
for performance statistics, and maintains these statistics inde-
pendently for each direction. Performance primitives are
collected and stored as performance parameters which are avail-
able for remote retrieval or local retrieval via the front-panel
craft terminal interface port.
6.1
Performance Primitives
Performance primitives are basic error events, or other perfor-
mance-related occurrences, monitored by the unit and stored as
performance parameters.
Line Performance Primitives
Bipolar Violation
BPV
Excessive Zeros
EXZ
Loss of Signal
LOS
Path Performance Primitives
CRC Error (ESF)
CRC6
Frame Bit Error (SF)
FE
Out of Frame
OOF
Severely Errored Frame
SEF
Alarm Indication Signal
AIS
6.2
Performance Parameters
The unit monitors, processes and stores the span’s performance
primitives as Line, Path and Miscellaneous parameters.
Line Performance Parameters
Coding Violation Line
CVL
Errored Seconds Line
ESL
Severely Errored Seconds Line
SESL
Loss of Signal Seconds Line
LOSS-L
Path Performance Parameters
Coding Violation Path
CVP
Errored Seconds Path
ESP
Severely Errored Seconds Path
SESP
Unavailable Seconds-Path
UASP
Miscellaneous Parameters
Pulse Density Violation Seconds
PDV-SEC
B8ZS Violation Seconds
B8ZS-SEC
Monitored Seconds
MSEC
6.3
Status Register (STAT)
The unit provides a Status Register for both directions of trans-
mission indicating various events that have occurred during a
particular monitoring window. The Status Register consists of
an 8-bit word with a 1" indicating an occurrence of a particular
event.
Event
Bit
Loopback
1
Data incomplete
2
Loss of Signal
3
Reserved
4
Power Loss
5
AIS
6
RAI (alarm yellow)
7
Out of Frame
8
6.4
Event/Alarm Log
The NIU features an Event/Alarm Log that registers various
events occurring during the monitoring period. The log provides
time-stamped entries for the most important types of events
such as loss of signal, power outages, PM registers cleared, alarm
detection, and more. Several different types of events are pos-
sible in the log as listed in the examples of Table 2. The
Event/Alarm Log will retain the 100 most recent events in non-
volatile memory. The Event/Alarm Log can be viewed locally via
