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15-4 August 2003 Access Navigator - Release 1.8
Diagnostics & Troubleshooting
Facility Alarm System
l
Alarm Cutoff (ACO)
l DS1 status
l Ethernet status
Facility Alarm System
The Access Navigator has alarm relay outputs for connection to the facility alarm system (see Alarm
Output Connections on page 6-27). Separate alarm outputs are provided for critical, major, and minor
alarms.
Alarm Cutoff (ACO)
The ACO function enables the operator to turn off all alarm relay outputs from the Access Navigator to
the facility alarm system. If logged into the Access Navigator via RS-232 or Telnet, use the aco
command (see ACO on page 18-23). If standing next to the Access Navigator, press the ACO pushbutton
switch on the Controller displaying the alarm indication (see Figure 15-2).
The ACO indicator will light while the alarm relays are cut off. The ACO function will be reset if a new
alarm event occurs with the same severity (critical, major, minor). Normal operation will resume when
all alarms have been cleared.
Alarm Signaling – Red, Yellow (RAI), Blue (AIS)
Traditional telecommunications alarm signals were assigned colors:
l RED – a local alarm such as LOF or LOS
l YELLOW – an alarm signal returned back toward the failure. The yellow signal is officially
called a Received Alarm Indicator (RAI).
l BLUE – an alarm signal forwarded to the next element. The blue signal is officially called an
Alarm Indication Signal (AIS).
Simply stated, when a DS1 network element sees red, it returns yellow and forwards blue.
The Access Navigator responds to received red and yellow DS1 alarm signals and detects Loss of Frame
(LOF) and Loss of Signal (LOS) alarms (see Figure 15-1). Blue alarms are not forwarded because the
Access Navigator is a 1:0 digital crossconnect switch (DCS). Instead of sending an all-ones blue alarm
pattern over the forwarded DS1s, the DS1 interface forwards an all-ones pattern over each affected DS0.
In a 1:0 DCS the 24 DS0s in each received DS1 may be split into different DS1 paths. Consequently,
DS1 blue alarm signaling is not allowed on the forwarded DS1s because this would interrupt valid
traffic on DS0s received by other DS1s.