If your Juniper SRX or EX does not come up with it’s JunOS operating system, you might be able to restore JunOS through the “boot-loader”. This article will show how.

Preparation

Repair with USB stick

  • The JunOS installation image (junos-srxsme-<version>-domestic.tgz) must be stored in the root directory of a FAT32 formatted USB stick.
  • The USB stick must be connected to the Juniper device before (re)boot.

Repair with TFTP server

  • The JunOS installation image (junos-srxsme-<version>-domestic.tgz) must be stored in the TFTP-server’s directory and must have the correct permissions (usually world readable) that it can be downloaded by TFTP.
  • The Ethernet cable through that the Juniper device can reach the TFTP-server must be connected to port 0 of the SRX or EX. But TFTP-server and Juniper device need not to be in the same network.

⚠ Many TFTP server cannot handle files larger than 90 MBytes. Since the installation image of JunOS has at least 130 MB, be sure to use a server that can handle it.

Activate the boot-loader

  1. Connect to the console of the Juniper device (9600,8,N,1).
  2. Reboot the SRX/EX and
  3. wait for the message 
    Loading /boot/defaults/loader.conf
    and a few lines later 
    Hit [Enter] to boot immediately, or space bar for command prompt
  4. Press Space to get to the Loader>-prompt

Load and install the JunOS operating system

… using USB

  1. Connect the USB stick
  2. Boot the device and access the boot-loader like described above.
  3. At the Loader>-prompt install the JunOS image with 
    install file:///junos-srxsme-12.1X46-D15.3-domestic.tgz
    ( 12.1X46-D15.3 is the JunOS Version in this example)
  4. After successful installation the Juniper device will boot automatically.

… using TFTP

  1. Boot the device and access the boot-loader like described above.
  2. At the Loader>-prompt set the environment variables according to your setup like in this example: 
    set ipaddr=192.168.1.2
set netmask=255.255.255.0
set gatewayip=192.168.1.1
set serverip=192.168.2.10
save
    (The SRX’s IP in this example is 192.168.1.2 and the TFTP-server’s 192.168.2.10.)
  3. Now install the JunOS image with 
    install tftp://192.168.2.10/junos-srxsme-12.1X46-D15.3-domestic.tgz
    ⚠ The IP address is the install command must match that one of the environment variable serverip.
  4. After successful installation the Juniper device will boot automatically.