Logging Operation

Logging

When a notification is generated by a NE, it is added to each log that exists in nlmConfigLogTable and satisfies the following conditions:

• The notification log is enabled and active.
• The security credentials associated with the log permit acces to the notification and all the var-binds contained in the notification. This condition does not apply to the default log as it is not associated with any security credentials.
• The filter associated with the log exists and is active and does not filter out the notification.

Before adding a notification to a log, the NE makes sure that the log size limits are not exceeded by this addition in the following manner:

• For logs with user defined size limits (i.e. nlmConfigLogEntryLimit is set to a value greater than 0):
  • If the number of entries in the log is equal to the entry limit of the log (nlmConfigLogEntryLimit), the oldest notification is removed from the log before adding the new notification to the log.
  • If the number of entries in the log is less than the entry limit of the log (nlmConfigLogEntryLimit), but the total number of entries in all logs combined is equal to the global entry limit (nlmConfigGlobalEntryLimit), then the oldest entry from the system managed log with the largest number of entries is removed before adding the new notification to the log.

Aging

Periodically (every minute), the notification log module calculates the difference between the current time and the time the notification entry is added to a log for each notification entry in each log. If the time difference is greater than the global age out period, the entry is removed from the log. Aging in this manner imposes a limitation that entries may be aged out sooner or later than the actual global age out period if the current time of the NE is changed (for example, to DST changes). Implementing age out accurately consumes 4 additional bytes of memory per notification entry.

Statistics

In ExtremeXOS Release 15.5, the following SNMP Notification Logs statistics are available:

• Total number of notifications that have been logged since the NE last restarted.
• Total number of notifications that have been removed due to size constraints since the NE last restarted.
• Per log number of notifications logged since the NE last restarted.
• Per log number of notifications removed due to size constraints since the NE last restarted.