What Are Alarms and Events?
An event is a distinct incident that occurs at a specific point in time, such as a port status change, or a device becoming unreachable. Events can indicate an errors, failures, or exceptional conditions in the network. Events can also indicate the clearing of those errors, failures, or conditions. Event have associated severities (which you can adjust as described in Change Alarm Severity Levels).
An alarm is a Cisco EPN Manager response to one or more related events. Only certain events generate alarms. Alarms have a state (cleared or not cleared) and a severity (Critical, Major, Minor, and so forth). An alarm inherits the severity of its most recent event. Alarms remain open until a clearing event is generated (or if the alarm is manually cleared).