324 CHAPTER 8: T HE E VENT LOGEvents may also be manually resolved. See “Manually Resolving Events”on page 334 for more information.Smart Event Analysis The Events System provides a set of features that work together to filterand interpret the generated events and provide you with the bestpossible picture of the state of your network. These features are eventcorrelation, recurring event handling, event suppression and SNMP trapfiltering, and are known collectively as Smart Event Analysis. See“Controlling Smart Event Analysis”on page 352 for more information.Event CorrelationThe event correlation feature analyzes the events that are beinggenerated, determines sets of events that have been caused by the sameissue, and replaces each set with a single event that more clearlydescribes the issue.For example, if there is a set of Device not responding and Link isunavailable events generated for a group of connected devices within ashort period of time, then the event correlator will analyze these events,determine that they are caused by a loss of connectivity to that section ofthe network and replace the set of events with a single Section ofnetwork down event.Recurring Event HandlingEvents may be generated repeatedly if a monitor regularly crosses athreshold or if the same SNMP trap type is received repeatedly from adevice. If all of these events were logged separately in the event systemthen they would quickly outnumber other events, making it difficult todetermine the real problems in your network.The recurring event handler helps avoid this situation by determiningwhen the same event is being generated repeatedly for a particulardevice or link, and then replacing all occurrences of the event with asingle event that has the recurring severity. The recurring event handlerthen continues to scan for further occurrences of this event, preventsthem from being logged and updates the already logged recurringseverity event with the total number of times that the event has beengenerated.Recurring events take longer to resolve than non-recurring events as3Com Network Director waits to ensure that no further events of thesame type and source are being generated.
