Logging Operation
This section discusses operation of the notification-log feature when a notification is
generated by the NE.
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 system managed logs (i.e. nlmConfigLogEntryLimit is set to 0):
- If 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.
- 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 (Simple Network Management Protocol) 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.