Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?




Hierarchy Level


Set the interval between the periodic signals broadcast to the devices in a chassis cluster to indicate that the active node is operational.

The heartbeat-interval option works in combination with the heartbeat-threshold option to define the wait time before failover is triggered in a chassis cluster. The default values of these options produce a wait time of 3 seconds. In a large configuration approaching full capacity on an SRX5400 or SRX5600 or SRX5800 device, however, we recommend that you increase the failover wait time to 5 seconds.

For example, a heartbeat-threshold of 3 and a heartbeat-interval of 1000 milliseconds result in a total wait of 3 seconds before failover is triggered. To increase this wait to 5 seconds, you could increase the heartbeat-threshold, the heartbeat-interval, or both. A heartbeat-threshold of 5 and a heartbeat-interval of 1000 milliseconds would yield a wait time of 5 seconds. Setting the heartbeat-threshold to 4 and the heartbeat-interval to 1250 milliseconds would also yield a wait time of 5 seconds.


In a chassis cluster scaling environment, the heartbeat-threshold must always be set to 8.


milliseconds—Time interval between any two heartbeat messages.

  • Range: 1000 through 2000 milliseconds

  • Default: 1000 milliseconds

Required Privilege Level

interface—To view this statement in the configuration.

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

Release Information

Statement introduced in Junos OS Release 9. Statement updated in Junos OS Release 10.4.