Carrier Access Access Navigator user manual Facility Alarm System, Alarm Cutoff ACO

Diagnostics & Troubleshooting

Facility Alarm System

￿￿Alarm Cutoff (ACO) ￿￿DS1 status ￿￿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:

￿￿RED – a local alarm such as LOF or LOS

￿￿YELLOW – an alarm signal returned back toward the failure. The yellow signal is officially called a Received Alarm Indicator (RAI).

￿￿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.

15-4 August 2003 Access Navigator - Release 1.8