Customers may observe high session table utilization or session table exhaustion on an SRX device when an application is configured with an inactivity timeout of never.

When the inactivity timeout is set to never, inactive sessions associated with the application are not cleared based on inactivity. Over time, a large number of inactive sessions may accumulate in the session table and consume available session resources.

Once the session table reaches its capacity, the SRX may be unable to establish or process new sessions, potentially resulting in traffic disruption or service impact.

Sample configuration:

set applications application custom-timeout-app inactivity-timeout never

Review the inactivity timeout configuration for applications that generate a large number of sessions.

Avoid configuring the inactivity timeout as never unless there is a specific requirement to maintain inactive sessions.

Configure an appropriate inactivity timeout based on the application's traffic pattern and requirements. For example:

set applications application custom-timeout-app inactivity-timeout 3600

The above configuration sets the inactivity timeout to 3600 seconds (1 hour).

Once an appropriate timeout is configured, inactive sessions can be cleared after the configured period, helping prevent unnecessary session-table consumption.