Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?


Upgrading Virtual Chassis Fabric Software Using Automatic or Standard Software Update Features

This topic describes the procedures that you can use to update software on an existing Virtual Chassis Fabric (VCF) that require VCF downtime during the upgrade operation.

To upgrade the software running on all member switches in an operational QFX5100 VCF with minimal network traffic disruption during the upgrade, you can use nonstop software upgrade (NSSU). See Upgrading Software on a Virtual Chassis Fabric Using Nonstop Software Upgrade.

Automatic Software Update

We recommend that you update the software on each device you include in a VCF to the same or a compatible version before initially interconnecting the VCF.

When you want to add new devices to an existing VCF, you can also update each new device to the same version of Junos OS software that is running on the VCF before cabling it into the VCF. Alternatively, you can configure the automatic software update feature, which automatically updates the software on a new device (to the same version already running on the VCF) when you cable it into the VCF.

To configure the automatic software update feature for a non-mixed VCF (a QFX5100 VCF composed entirely of QFX5100 switches, or a QFX5110 VCF composed either exclusively of QFX5110 switches or both QFX5110 and QFX5100 switches), specify the common package name for the Junos OS image that runs on all the switches in the VCF, with no other options, as follows:


A QFX5110 VCF is considered to be a non-mixed VCF whether it includes QFX5100 switches or is composed exclusively of QFX5110 switches. Because both types of switches run the same software image when interconnected into a QFX5110 VCF, you can use the auto-sw-update command with one software package name for all members.


You must first upgrade a QFX5100 switch running a Junos OS software image with “-qfx-5-” in the software package filename to a Junos OS software image with “-qfx-5e-” in the package filename before it can be added to a QFX5110 VCF. The automatic software update process can’t update a switch from a “-qfx-5-” image to a “-qfx-5e-” image. See Upgrading a QFX5100 Switch with a USB Device to Join a QFX5110 Virtual Chassis or Virtual Chassis Fabric.

After a QFX5100 switch is installed with a “-qfx-5e-” Junos OS software image, the automatic software update process can successfully update the switch automatically with a different version of a “-qfx-5e-” Junos OS image to match the other members in the VCF.

To configure the automatic software update feature on a mixed QFX5100 VCF composed of QFX5100 devices and at least one other type of device, you must specify the package name for each type of device in the mixed VCF using a separate command with the associated platform-specific option:

The options specify package names for different platforms as follows:

  • qfx-5: package-name is the path to a compatible Junos OS image for QFX5100 devices.

  • qfx-3: package-name the path to a compatible Junos OS image for QFX3500 or QFX3600 devices.

  • ex4300: package-name the path to a compatible Junos OS image for EX4300 switches.

If the software package is located in a local directory on the device, use the following format for package-name:


If the update process will download the software package from a remote location, use one of the following formats:



Standard Upgrade

You can upgrade software on a VCF using the traditional method of upgrading software for Junos OS by logging onto the primary Routing Engine and using the request system software add command to initiate the upgrade on a non-mixed VCF or the request system software add set [package-name package-name ...] to initiate the upgrade on a mixed VCF, where package-name is the path to an image for one device family.

When you upgrade Junos OS on a VCF using the traditional software upgrade, each device in the VCF must reboot. The entire system is down until the upgrade process is complete.

For information on performing this procedure, see Installing Software Packages on QFX Series Devices.