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Flow-Based Performance

This topics explains about the performance of the session capacity. Expanding the session capacity and reverting back to the default session capacity.

Expanding Session Capacity by Device

To take advantage of the processing potential of a fully loaded SRX5600, SRX5800 device, or vSRX Virtual Firewall, you can expand the maximum number of concurrent sessions for these devices.

Table 1 shows the maximum number of concurrent sessions allowed on these devices by default and with expanded capacity. Platform support depends on the Junos OS release in your installation.

Table 1: Maximum Central Point Session Increases

SRX Series Devices

Maximum Concurrent Sessions on a Fully Loaded System


With Expanded Capacity


2.25 million

3 million


2.25 million

6 million


42 million

Expansion not available


114 million

Expansion not available


258 million

Expansion not available


6 million

Expansion not available


25 million

Expansion not available

The method used for expanding session capacity depends on the device:

  • Central point session license installation and validation on an SRX3400 or SRX3600 device

  • CLI optimization option on an SRX5800 device

Expanding Session Capacity on an SRX3400 or SRX3600 Device

Expanding session capacity on an SRX3400 or SRX3600 device requires validation of a central point session license on the device.

  1. Obtain the central point session license key and install the license on the device..

  2. Reboot the device to implement the expanded session capacity.

Reverting to Default Session Capacity on an SRX5800 Device

Reverting to the default session capacity on an SRX5800 device requires a CLI configuration change.

  1. Enter the following command at the CLI configuration prompt to reestablish the default session capacity value:

  2. Commit the configuration.

  3. Reboot the device to implement the new value.

Verifying the Current Session Capacity


The central point session summary includes the maximum sessions setting for the device. From this value you can determine if the session capacity has been modified as you expected.


To verify the current setting of the central point session capacity, enter the following CLI command.


The Maximum sessions value reflects the current session capacity on your device. A value of 14000000 means that the SRX5800 device is configured for the expanded number of central point sessions.