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.