Instruction manual

FEATURES AND SERVICES
System Maintenance
Description
The primary objective of System 25 maintenance is to detect, report, and clear troubles as
quickly as possible and with minimum disruption to normal service. This goal is supported
by periodic automatic diagnostic tests and fault detection hardware. System design allows
most troubles to be resolved to the circuit pack level.
System 25 hardware and software are organized as independent units or maintenance
objects. Each maintenance object is normally a separately replaceable unit. These units
include circuit packs, power units, fans, voice and data terminals, cross-connect hardware,
auxiliary, and peripheral equipment.
There are two general categories of system errors:
system-detected errors and user-
reported problems.
The system can automatically detect and log errors without human
intervention. For system-detected errors, an Alarm LED on the Attendant Console is lighted
if the error qualifies as a Permanent System Alarm (a serious error). Most alarms can be
verified by checking the LEDs located on the front edge of the system circuit packs. (At least
one Red LED will be on.) User-reported problems are usually detected at individual voice
and data terminals and are often related to alarmed conditions.
Alarms may be retired automatically and can also be cleared manually. After a trouble has
been cleared, the system retests the previously faulty area.
If the fault is no longer present,
the error message (and alarm, if applicable) is cleared.
It is not necessary for maintenance
personnel to retire alarms after a problem has been fixed. However, they may clear error
messages and alarms by entering the proper commands at the System Administration
Terminal.
System Errors And Alarms
If a maintenance object fails periodic tests, the system automatically generates an error
record that is placed in one of three software tables (error logs). The failure may be
classified as a Permanent System Alarm or as an unverified failure that never becomes a
Permanent System Alarm.
A Permanent System Alarm causes the Alarm LED on the
Attendant Console to light.
This alarm indication is a signal to the attendant to contact
maintenance personnel.
System alarms are classified as:
● Permanent System Alarms: Failures that cause degradation of service and require
Immediate attention. These alarms cause the Alarm LED on the Attendant Console
to light and an alarm record to be stored in the Permanent System Alarm error log.
● Transient System Errors: Potential failures that may cause degradation of service.
These do not light the Alarm LED on the Attendant Console. These are errors that
have not been verified by system self-tests, and are not yet serious enough to be
classified as Permanent System Alarms.
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