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Upgrading/Downgrading/Reinstalling Junos



Article ID: KB11409 KB Last Updated: 28 Dec 2018Version: 9.0

Your routing platform comes with Junos software installed on it. When you power on the router the software starts automatically; no need to download software, just configure the software so that the router will be ready to participate in the network..

The Junos software is installed on the router’s flash disk (a nonrotating drive) and hard disk (a rotating disk). A copy of the software also is provided on removable media, either a PC Card or USB storage device, which can be inserted into the router’s card slot. By default, when you power on the router, it runs the copy of the software that is installed on the flash disk. Note, the software on the PCMCIA or USB is a bootable image and different from the software bundle you can download from the CSC web page.

You can upgrade the router software as new features are added or software problems are fixed, install individual packages, or reinstall the current version.

  • Which software download package do I use?
  • Do I need to upgrade any hardware components?
  • Can I downgrade the software?
  • What is the boot sequence the hardware uses?

Note: These instructions are also provided in the Technical Documentation under your specific product and version of Junos.

Before upgrading or downgrading your system, check the Junos Release Notes for any hardware or software limitations or changes.  Release Notes are posted on the Technical Documentation page associated with your Junos version or in the Download Software area.

Selecting an Installation Package, Storage Media, and Boot Sequence Information

Which Installation Package to Use:

The Junos software from the Juniper Networks Support Download page provides three installation packages. A package is a collection of files that make up a software component.
  • jinstall—An Install Package used to upgrade or downgrade  from Junos Releases (example: upgrading from 7.x to 8.x or 8.x to 8.x) or when the software becomes damaged and needs to be reinstalled. In general, always use jinstall unless directed by a Juniper Networks support representative. The jinstall package completely reinstalls the software.

  • jbundle—A Software Bundle used to downgrade from Release 8.x. jbundle is also used to upgrade or downgrade between minor versions of the Junos software. jbundle modifies the smallest set of files needed to change to the new software version.

  • junos-jseries—An Install Bundle used to install the Junos J-series software on J-series Services Routers.

    jweb (the J-Web package within this bundle, and the jinstall and jbundle packages) contain the J-Web graphical user interface software for managing J-series, M-series, MX-series, and T-series routing platforms.

Storage Media 

Storage Media - The router has three forms of storage media; Flash disk, Hard disk, and removable media. Each comes with Junos system software preinstalled. The router can boot from the flash disk, the hard disk, or a removable medium. The disk from which the router boots is called the primary boot device, and the other disk is the alternate boot device.
  • Flash disk, which is a nonrotating drive.
  • Hard disk, which is a rotating drive. This drive also is used to store system log files and diagnostic dump files.
  • Removable media, which is either a PC Card, USB storage device, or LS-120 floppy disk. Do not insert the removable media during normal operations. The router does not operate normally when it is booted from the removable media.
For a list of Routing Engines by Routing Platform and Storage Media Names, refer to the Software Installation and Upgrade guide.

warning: Notable exceptions:
  • Flash Disk Requirements: For M-series, MX-series, and T-series routing platforms - The compact flash disk memory requirement for Junos software Release 9.0 is 1 GB. For M7i and M10i routing platforms with only 256 MB of memory, see the Support Technical Bulletin PSN-2007-10-001 (CSC login required)
  • On the M7i and M10i routing platforms, the default configuration of the Routing Engine-400 does not include an internal compact flash disk. Because of this, the router boots from the hard disk. There is no alternate boot device.

Boot Sequence

Boot Sequence - Each media location (the internal flash disk, the hard drive, or the removable media) has the ability to load the software into memory and boot the router, but the primary boot media is the internal flash disk. The hard drive is considered the secondary boot location, while the removable media is used for disaster-recovery purposes.
Note: A “factory fresh” router has the most recent Junos software version installed on the internal flash disk as well as the removable media
As the router boots, it first runs a power-on self-test (POST) to verify that the basic system components are operating normally. The router then locates a copy of the Junos software and loads it into memory. The boot sequence of the router is:
  1. Removable media (if installed)
  2. Flash disk (Primary Boot media)
  3. Hard disk (Secondary Boot media)
The removable media is the first boot location examined. If the router finds a copy of the Junos software there, it loads the software on the router. This presents a possible hazard in your network since all existing files and file systems on the router are erased during this process. This type of boot process returns the router to a factory default-type environment and should be used only for disaster recovery. If no removable media is present, the router loads the software from the internal flash disk. This is considered the normal boot operation and should occur at each router start.


When upgrading or downgrading Junos software, we recommend that you include the validate option with the request system software add command to check that the candidate software is compatible with the current configuration. By default, when you add a package with a different release number, the validation check is done automatically. For more information about the request system software add command, see the Overview for Junos OS for your release.

In the more recent Junos software versions, during software installation, the configuration checker in the installation program checks the router’s PICs. If any configuration rules affect your PIC combinations, the installation process stops and displays a message

For more information about checking for unsupported PIC combinations, see the corresponding PIC guide for your router, the Junos Release Notes, and the Technical Support Bulletins (such as PSN2007-11-008); all are accessible from Juniper Networks Support.

For All Software Packages
  • When upgrading from Junos Release 8.2 or below to Junos Release 8.5, use the system software add <image> no-validate command option.
  • Only use the jinstall Junos software image when upgrading or downgrading to or from Junos Release 8.5.  Do not use the jbundle image.
  • Before upgrading to Junos Release 8.5, ensure that the routing platform has a CF card with a minimum of 256 MB storage space to avoid disk size restrictions.
  • For hard disks that were formatted using Junos Release 4.4 or below, after you issue the request system snapshot partition command, use the request system snapshot command before upgrading.

Select from one of the following tasks:

Upgrade / Downgrade All Software Packages
Upgrade Individual Software Packages
Reinstall Software Package

To Upgrade / Downgrade All Software Packages, use the jinstall package. Follow these steps:
  1. Connect to the router console port using an out-of-band connection. Use an out-of-band connection from the console, because in-band connections are lost during the upgrade process.
  2. Back up the currently running and active file system so that you can recover to a known, stable environment in case something goes wrong with the upgrade. The upgrade process using the jinstall package removes stored files on the router, except juniper.conf and SSH files.
    To copy the files to the router’s hard disk, use the following command:

    user@host> request system snapshot

    The /root file system is backed up to /altroot, and /config is backed up to /altconfig. The /root and /config file systems are on the router’s flash disk, and the /altroot and /altconfig file systems are on the router’s hard disk.
  3. Download the jinstall software package from Juniper Networks Download Software site. Choose the Canada and U.S., Worldwide, or Junos-FIPS edition. Place the package on a local server.
    To download the jinstall package, you must have a service contract and an access account.  Contact the Customer Care team if you do not have an account.

    note: Downgrading by more than three releases is not supported. For example, if your routing platform is running Junos Release 7.5, you can downgrade directly to Release 7.2, but you cannot downgrade directly to Release 7.1. As a workaround, you can first downgrade to Release 7.2 and then downgrade to Release 7.1. See the release notes for each software release for details.
  4. Copy the jinstall package to the router. We recommend that you copy it to the /var/tmp directory, which is a large file system on the hard disk.
    user@host>file copy ftp://[username:prompt]@[]/[filename]  /var/tmp/

    user@host>file copy /var/tmp/

    Note: Remember to use binary mode when transferring files via FTP.
  5. Install the new software package, as shown below, where package-name is the full filename. 7.x is the major software release number; for example, 7.5R2.8. Use the reboot option to start the new software after it is loaded.
    user@host> request system software add [package location]/[package name] reboot

    user@host>request system software add " reboot
    user@host>request system software add /var/tmp/7.5R2.8/jinstall-7.5R2.8-domestic-signed.tgz reboot

    For more information about the request system software add validate command, see the Overview for Junos OS
    Sample output:

    user@host>request system software add " reboot

    Reboot the system? [yes,no] (no) yes
    Shutdown NOW!
    Reboot consistency check bypassed - jinstall 7.5R2.8 will complete installation upon reboot
    *** FINAL System shutdown message from user@host-re0 ***
    System going down IMMEDIATELY

    All the software is loaded when you reboot the system. Installation can take between 5 and 10 minutes. The router then reboots from the boot device on which the software was just installed. When the reboot is complete, the router displays the login prompt. While the software is being upgraded, the Routing Engine on which you are performing the installation is not routing traffic.

    note: You must reboot to load the Junos software. To reboot, issue the request system reboot command when you are finished installing the software.

    note: To terminate the installation, do not reboot your system; instead, finish the installation and then issue the request system software delete jinstall command. This is your last chance to stop the installation. If Junos software does not install properly, you must install from the removable media.
  6. Log in and verify the version of software running after the router reboots. Issue the show version command.
  7. Add the optional jweb package using the request system software add command if you have already downloaded and copied it to the /var/tmp directory.
  8. After you have upgraded or downgraded the software and are satisfied that the new software is successfully running, issue the request system snapshot command to back up the new software.
    The request system snapshot command causes the root file system to be backed up to /altroot, and /config to be backed up to /altconfig. The root and /config file systems are on the router’s flash disk, and the /altroot and /altconfig file systems are on the router’s hard disk.

    note: After you issue the request system snapshot command, you cannot return to the previous version of the software, because the running copy and backup copy of the software are identical.

Upgrade Individual Software Packages

Under normal circumstances, this process is not needed (except for jfirmware, webui)
  1. Repeat steps 1 through 4 from the Upgrade / Downgrade section above.
  2. If you are copying multiple software packages to the router, copy them to the /var/tmp directory on the hard disk:
    user@host> file copy  /var/tmp/
  3. Add the new software package:
    user@host> request system software add /var/tmp/package-name-signed.tgz validate

    The system might display the following message:

    pkg_delete: couldn’t entirely delete package

    This message indicates that someone manually deleted or changed an item that was in a package. You do not need to take any action; the package is still properly deleted.

    If you are upgrading more than one package at the same time, add jbase first. If you are using this procedure to upgrade all packages at once, add them in the following order:

    user@host> request system software add /var/tmp/jbase-release-signed.tgz
    user@host> request system software add /var/tmp/jkernel-release-signed.tgz
    user@host> request system software add /var/tmp/jpfe-release-signed.tgz
    user@host> request system software add /var/tmp/jdocs-release- signed.tgz
    user@host> request system software add /var/tmp/jweb-release- signed.tgz
    user@host> request system software add /var/tmp/jroute-release-signed.tgz
    user@host> request system software add /var/tmp/jcrypto-release-signed.tgz
  4. Reboot the router to start the new software:
    user@host> request system reboot
  5. After you have upgraded or downgraded the software and are satisfied that the new software is successfully running, issue the request system snapshot command to back up the new software.
    user@host> request system snapshot

    The root file system is backed up to /altroot, and /config is backed up to /altconfig. The root and /config file systems are on the router’s flash disk, and the /altroot and /altconfig file systems are on the router’s hard disk.

Reinstall a Software Package
  1. Repeat steps 1 through 4 from the Upgrade / Downgrade section above.
  2. Copy the jinstall package to the /var/tmp directory on the hard disk:
    user@host>file copy  /var/tmp/
  3. Add the jinstall package:
    user@host> request system software add /var/tmp/jinstall-8.x-package-name-signed.tgz
  4. If you want, add the optional jweb package. For more information, consult the Junos Software Installation and Upgrade Guide.
  5. Reboot the router to load the Junos software:
    user@host> request system reboot
Modification History:
2018-12-28: updated links.

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