4 System Management Functions
Last update PvD

Alarm Reporting Function

Recommendation X.733.


  1. CMIP Notification
  2. Event Type
  3. Event Information
  4. List of Probable Causes

CMIP Notification

X.733 Alarm Reporting is primarily about the alarm as a CMIP message.  As alarm messages are CMIP 'Event Reports', some parameters are generic CMIP:

So the CMIP message already identifies the originating object (i.e. the object issuing an alarm).

An 'Alarm record' is a managed object class derived from the Event log record object class defined in CCITT Rec. X.721 | ISO/IEC 10165-2.  The Alarm record object class represents information stored in logs as a result of receiving an event report where the event type is one of the alarm types defined in this Recommendation | International Standard.

Event Type

Event type consists of one of the following Alarm types:

See also the predefined List of Alarms below.

Event Information

Event information (fields are optional unless explicitly stated otherwise):

Alarm Severity

The Perceived severity field in Event information can have the following values:

In practice, the Severity of a fault is less straightforward.  When a section of a transmission link is cut, the severity will probably be Critical.  However, when that section is protected like in an SDH-ring, it will only be Minor at most.  If there is no ring protection, but paths are potentially protected on individual basis, it is unclear what severity this fault must get.  See also (MFA) Fault Management Alarm surveillance.

List of Probable Causes

[X.721] already defines a list which can be extended using ASN.1 (most systems do that).

Alarm typeProbable cause
CommunicationsLoss of signal
Loss of frame
Framing error
Local node transmission error
Remote node transmission error
Call establishment error
Degraded signal
Communications subsystem failure
Communications protocol error
LAN error
DTE-DCE interface error
Quality of serviceResponse time excessive
Queue size exceeded
Bandwidth reduced
Retransmission rate excessive
Threshold crossed
Performance degraded
Resource at or nearing capacity
Processing errorStorage capacity problem
Version mismatch
Corrupt data
CPU cycles limit exceeded
Software error
Software program error
Software program abnormally terminated
File error
Out of memory
Underlying resource unavailable
Application subsystem failure
Configuration or customization error
EquipmentPower problem
Timing problem
Processor problem
Dataset or modem error
Multiplexer problem
Receiver failure
Transmitter failure
Receive failure
Transmit failure
Output device error
Input device error
I/O device error
Equipment malfunction
Adapter error
EnvironmentalTemperature unacceptable
Humidity unacceptable
Heating/ventilation/cooling system problem
Fire detected
Flood detected
Toxic leak detected
Leak detected
Pressure unacceptable
Excessive vibration
Material supply exhausted
Pump failure
Enclosure door open

Most alarm handlers provide additional functionality, like keeping a list of active alarms sorted on severity or area, count repeating alarms, etc.

See also (Management Functional Area) Fault Management.

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