What is the alarm purge algorithm?

Overview

Because a large number of outstanding alarms can affect system performance, the NFM-P purges outstanding alarms. The alarm purge algorithm sorts alarms using the following criteria:

• lower severity alarms are deleted before higher severity alarms

• within a severity, the oldest alarms are always deleted first

Note: The alarm purge algorithm is not applied to the following correlating—or root cause—alarms unless the red threshold has been crossed:

• EquipmentRemoved

• EquipmentMismatch

• EquipmentDown

• EquipmentAdministrativelyDown

• ContainingEquipmentMissing

• ContainingEquipmentMismatch

• ContainingEquipmentAdministrativelyDown

• ContainingEquipmentOperationallyDown

• TunnelDown

• TunnelAdministrativelyDown

• AccessInterfaceDown

• SdpBindingDown

When an alarm policy does not exist, the NFM-P purges alarms as follows:

For collocated systems:

• If the outstanding alarm count reaches 45 000, the NFM-P:

  • raises an alarm to indicate that an alarm purge is in progress

  • purges non-critical alarms not in the exclusions list to the historical alarm log until the count drops to 45 000

• If the outstanding alarm count reaches 60 000, the NFM-P:

  • raises an alarm to indicate that an alarm purge is in progress

  • purges alarms to the historical alarm log, starting with the oldest lowest severity alarms, until the count drops to 45 000

  • displays “Max alarm count exceeded” in the status bar

For distributed systems:

• If the outstanding alarm count reaches 200 000, the NFM-P:

  • raises an alarm to indicate that an alarm purge is in progress

  • purges non-critical alarms not in the exclusions list to the historical alarm log until the count drops to 200 000

• If the outstanding alarm count reaches 250 000, the NFM-P:

  • raises an alarm to indicate that an alarm purge is in progress

  • purges alarms to the historical alarm log, starting with the oldest lowest severity alarms until the count drops to 200 000

  • displays “Max alarm count exceeded” in the status bar

To ensure that purged alarms are logged, you must enable alarm history logging. See How do I configure alarm history logging? for information about configuring alarm history logging and purging policies.