Starting in Junos OS Releases 17.3R2 and 17.4R1, you are not required to use the USB install method to upgrade a QFX5100 switch from a QFX 5 Series to a QFX 5e Series image. Instead, you can install the “QFX 5e Series” package directly using the CLI command  request system software add . See  Installing a Standard Software Package on QFX5000 and EX4600 Switches  for details on using the CLI install method.

With releases prior to Junos OS Release 17.3R2 or 17.4R1, you must use this USB install method due to the differences in the boot structure and host OS software of the two types of devices.​

The purpose of this knowledge base (KB) article is to outline QFX5100 requirements prior to creating a mixed QFX5110 / QFX5100 Virtual Chassis (VC), and instructions for upgrading the QFX5100 by using a bootable USB.  There are additional requirements for creating the QFX5110 / QFX5100 Virtual Chassis (VC), and are outlined below. 

• Caution : A QFX5100 switch running a Junos OS software image with “-qfx-5- ” in the package filename must first be upgraded to a Junos OS software image with “ -qfx-5e- ” in the package filename before it can be added to a QFX5110 Virtual Chasis or VCF. See  Upgrading a QFX5100 Switch with a USB Device to Join a QFX5110 Virtual Chassis or Virtual Chassis Fabric .

• Note : If a QFX5100 switch is already running a ”QFX 5e Series” image (software package filename contains the string “ -qfx-5e- ”), you are not required to use this procedure to upgrade the switch before adding it to a QFX5110 Virtual Chassis or VCF. The Virtual Chassis or VCF can successfully update a QFX5100 member to the same version of Junos OS using the usual supported software update methods as needed during initial configuration or when adding or replacing members. See  Understanding Software Upgrades in a QFX Series Virtual Chassis  and  Understanding Software Upgrades in a Virtual Chassis Fabric .

• QFX5100 USB Upgrade: If the QFX5100 has the “ -qfx-5- “ installed, then you must do a USB install to upgrade it to the “ -qfx-5e- “ image prior to adding it to the QFX5110 Virtual Chassis.  The QFX5110 already has the “ -qfx-5e- “ image installed.  Subsequent upgrades to the QFX5110 / QFX5100 Virtual Chassis do not require a USB installation. 

• Both QFX5110 and QFX5100 switches can run the  same   “ -qfx-5e- ” software images, and when inter-operating in a Virtual Chassis or VCF, they must be running the same “ -qfx-5e- ” software image that automatically either employs the secure-boot method (when booting on QFX5110 switches) or does not (when booting on QFX5100 switches).

• Due to platform and image differences, for a QFX5100 running a “ -qfx-5- ” image to successfully join a QFX5110 Virtual Chassis or VCF, you must initially upgrade the QFX5100 switch to run a “ -qfx-5e- ” image using a USB boot device  without  using the secure-boot method.

QFX5110 / QFX5100 Virtual Chassis Support

The QFX5110 / QFX5100 Virtual Chassis is supported starting from Junos 17.3R1.10 for the following models:

• QFX5110-32Q
• QFX5110-48S
• QFX5100-24Q
• QFX5100-48S
• QFX5100-96S 

NOTE : Support for the QFX5100-48T in a QFX5110 Virtual Chassis (VC) was added in Junos 17.3R1-S1.6

NOTE : Following an upgrade from qfx-5 to qfx-5e, all contents under /var/log and host os logs are removed, as the underlying host os is replaced during the upgrade procedure.

QFX5100 - USB UPGRADE PROCEDURE:

CHECK THE CURRENT JUNOS VERSION ON THE QFX5100:

• From CLI execute the “ run show version ” command. If it does not show " qfx-5e " or " QFX5100e " you need to upgrade the device using bootable USB
   

  Example:
  
  qfx -5 version
  
  {master:0}
root> show virtual-chassis 
 
Virtual Chassis ID: 2633.d6a5.0b0e
Virtual Chassis Mode: Enabled
                                                Mstr           Mixed Route Neighbor List
Member ID  Status   Serial No    Model          prio  Role      Mode  Mode ID  Interface
0 (FPC 0)  Prsnt    TA0000000053  qfx5100-48s-6q   128  Master*      N  VC
 
Member ID for next new member: 1 (FPC 1)
 
{master:0}
root> show version    
localre:
--------------------------------------------------------------------------
Model:  qfx5100-48s-6q
Junos: 17.3R1.10
  
  qfx -5e version 
  
  {master:0}
root> show virtual-chassis 
 
Virtual Chassis ID: 2633.d6a5.0b0e
Virtual Chassis Mode: Enabled
                                                Mstr           Mixed Route Neighbor List
Member ID  Status   Serial No    Model          prio  Role      Mode  Mode ID  Interface
0 (FPC 0)  Prsnt    TA0000000053  qfx5100e-48s-6q   128  Master*      N  VC
 
Member ID for next new member: 1 (FPC 1)
 
{master:0}
root> show version    
localre:
--------------------------------------------------------------------------
Model:  qfx5100e-48s-6q
Junos: 17.3R1.10
 

CREATE THE BOOTABLE USB WITH THE “-qfx-5e-“ IMAGE:

1. When creating the USB boot device to upgrade a QFX5100, you download the install media filename without the “secure” keyword 

   Example:
   install-media-host-usb-qfx-5e-x86-64-17.3R1.10.img
   
   Please refer to KB34749-[QFX] How to perform format installation on QFX5K via USB [juniper.net] for the format install procedure

2. Copy the “ -qfx-5e- “ image to the USB device and /var/tmp directory:

   • File name: install-media-host-usb-qfx-5e-x86-64-17.3R1.10.img 
   • Copy the file to /var/tmp of the USB device

3. Create the bootable USB: 

   root@device% dd if=/var/tmp/install-media-host-usb-qfx-5e-x86-64-17.3R1.10.img of=/dev/da1 bs=1m  
   
   The device writes the installation media image to the USB device.
   
   Example:
   
   root@device% dd if=install-media-host-usb-qfx-5e-x86-64-17.3R1.10.img of=/dev/da0 bs=1m  
1399+0 records in 
1399+0 records out 
1466957824 bytes transferred in 394.081902 secs (3722469 bytes/sec)

UPGRADE THE QFX5100 SWITCH WITH THE “-qfx-5e-“ IMAGE:

1. Insert USB into the USB port on the switch and power cycle by using the following command:

   “ request system reboot hypervisor ”

2. The switch will come online when booting from the USB device and running the Juniper Linux Installer.

   The installer menu prompts you to with the following options:
   
   Juniper Linux Installer - (c) Juniper Networks 2014
Reboot
Install Juniper Linux Platform        < ======USE THIS OPTION!
Boot to host shell [debug]
   
   To select the correct menu option, use the tab key to move through the options.   Select Install Juniper Linux Platform, and then press Enter.
   

3. Once the switch comes online, check the version by running the “ show version ” command from CLI:

   Example:
   {master:0}
root> show virtual-chassis
 
Virtual Chassis ID: 2633.d6a5.0b0e
Virtual Chassis Mode: Enabled
                                                Mstr           Mixed Route Neighbor List
Member ID  Status   Serial No    Model          prio  Role      Mode  Mode ID  Interface
0 (FPC 0)  Prsnt    TA0000000053 qfx5100e-48s-6q 128  Master*      N  VC
 
Member ID for next new member: 1 (FPC 1)
 
{master:0}
root> show version   
localre:
--------------------------------------------------------------------------
Model: qfx5100e-48s-6q
Junos: 17.3R1.10

2020-03-03: Added link to KB34749 [juniper.net] in creating the bootable USB section.
2020-07-02: Added paragraph in the summary about USB install not being needed for latest Junos release.
2025-10-13: Added clarification regarding the loss of syslogs after upgrading to qfx-5e

• Understanding QFX Series Virtual Chassis
• Understanding QFX Series Virtual Chassis Components
• Configuring a QFX Series Virtual Chassis (CLI Procedure)
• Upgrading a QFX5100 Switch with a USB Device to Join a QFX5110 Virtual Chassis or Virtual Chassis Fabric