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critical-event (System)


Hierarchy Level


Indicates an event that, if left unchecked, may result in serious loss of service or interruption of traffic. At the system level you can monitor the overall free pages (cache and free pages), kernel memory allocations and compare them with threshold values. You can also monitor the swap usage and specify the threshold for swap space usage. Most devices have a swap partition that you can configure to provide additional transient memory. Ideally, the swap partition is used only under exceptional circumstances. In current dynamic systems, you can sporadically use the swap partition as long as the usage is not high or persistent. For instance, you could categorise a critical event as one where the swap usage is greater than 75%.

You can only configure swap usage threshold for memory monitoring. If you do not configure the swap usage threshold, memory monitoring for swap usage is based on the default threshold. Memory monitoring for other features is based on the default threshold.



Specifies the process threshold level for a minor event. You must specify the process name and the memory limit for the process.


Specifies the swap usage in percentage.


Specifies the action to be performed when the threshold is crossed.

Required Privilege Level

system—To view this statement in the configuration.

system-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 20.1.