Facility alarms vs. log events

Facility Alarms are different than log events. Facility alarms have a state (at least two states: active and clear) and a duration, and can be modeled with state transition events (raised, cleared). A log event occurs when the state of some object in the system changes. Log events notify the operator of a state change (for example, a port going down, an IGP peering session coming up, and so on). Facility alarms show the list of hardware objects that are currently in a bad state. Facility alarms can be examined at any time by an operator, whereas log events can be sent by a router asynchronously when they occur (for example, as an SNMP notification or trap, or a syslog event).

While log events provide notifications about a large number of different types of state changes in SR OS, facility alarms are intended to cover a focused subset of router states that are likely to indicate service impacts (or imminent service impacts) related to the overall state of hardware assemblies (cards, fans, links, and so on).

The facility alarm module processes log events to generate the raised and cleared state for the facility alarms. If a raising log event is suppressed under event-control, then the associated facility alarm is not raised. If a clearing log event is suppressed under event-control, then it is still processed for the purpose of clearing the associated facility alarm. If a log event is a raising event for a Facility Alarm, and the associated Facility Alarm is raised, then changing the log event to suppress clears the associated Facility Alarm.

Log event filtering, throttling and discarding of log events during overload do not affect facility alarm processing. In all cases, non-suppressed log events are processed by the facility alarm module before they are discarded.

Figure: Log events, facility alarms and LEDs illustrates the relationship of log events, facility alarms and the LEDs.

Figure: Log events, facility alarms and LEDs

Facility alarms are different and have independent functionality from other uses of the term alarm in SR OS such as:

Parent topic: Facility alarms