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Junos OS Evolved Installation Packages

SUMMARY The installation package is used to upgrade or downgrade from one Junos OS Evolved release to another. When added, the installation package completely re-installs the software, rebuilds the file system, and can erase system logs and other auxiliary information from the previous installation. The system does, however, retain the configuration files from the previous installation.

The names of the Junos OS Evolved installation packages have the following general pattern:

  • prefix-release-edition.iso

Juniper Networks delivers the Junos OS Evolved software in signed packages that contain digital signatures. The system only installs a package if the checksum within it matches the hash recorded in its corresponding file.

Junos OS Evolved Installation Package Prefixes

The first part of the installation package filename is a combination of a standard prefix and a product designation.

Table 1: Installation Package Prefixes
Prefix Description

junos-evo-install* or junos-evo-install-media*

Introduced as of Junos OS Evolved Release 18.3R1. For Junos OS Evolved, there is a single image for all fixed form (versus chassis) platforms, and a platform image name can also be distinguished as merchant silicon (ms). Starting in Junos OS Evolved Release 20.3R1, install packages are available in limited editions. See Junos OS Evolved Editions. Here are some examples:

  • junos-evo-install-acx-qfx-7k-x86-64-release.iso—A single ISO image for the ACX7100 platforms.

  • junos-evo-install-acx-t-x86-64-release.iso—A single ISO image for the ACX6160 platforms.

  • junos-evo-install-acx-x86-64-release.iso—A single ISO image for ACX chassis platforms.

  • junos-evo-install-ptx-fixed-x86-32-release.iso—All fixed PTX platform variants (that is, PTX10001-36MR, and so on) have a single ISO image.

  • junos-evo-install-ptx-fixed-x86-64-release.iso—All fixed PTX platform variants (that is, PTX10003, and so on) have a single ISO image. For PTX orders, this image is installed as factory default.

  • junos-evo-install-ptx-chassis-x86-64-release.iso—One single ISO image for PTX chassis platforms.

  • junos-evo-install-qfx-ms-fixed-x86-64-release.iso—Single image for all QFX platforms based on merchant silicon. It could be the Broadcom family or any other vendor.

  • junos-evo-install-qfx-fixed-x86-64-release.iso—All fixed QFX platform variants have a single ISO image. For QFX orders, this image is installed as factory default.

  • junos-evo-install-qfx-chassis-x86-64-release.iso—One single ISO image for QFX chassis platforms.

Junos OS Evolved Release Numbers


Junos OS Evolved uses the same release numbering system as Junos OS.

Each release has certain new features that complement the software processes that support Internet routing protocols, control the device’s interfaces and the device chassis, and allow for device system management. From the web page for Juniper Networks Software Downloads, you download software for a particular release number.

In this example, we dissect the format of the software release number in the installation package to show what it indicates. The generalized format is as follows:

Given the format of:

  • m.nZb.s-EVO

The software release number 20.4R1.17-EVO, for example, maps to this format as follows:

  • m is the main release number of the product, for example, 20.

  • n is the minor release number of the product, for example, 4.

  • Z is the type of software release, for example, R for an FRS or a maintenance release.

    For types of software releases, see Table 2.

  • b is the build number of the product, for example, 1, indicating the FRS rather than a maintenance release.

  • s is the spin number of the product, for example, 17.

  • -EVO means that it is a Junos OS Evolved package.

Table 2: Software Release Types
Release Type Description


First revenue ship (FRS) or maintenance release software. R1 is FRS. R2 is a maintenance release.


Beta release software.


Internal release software. These packages are private software releases for verifying fixes.


Service release software, released to customers to solve a specific problem—Juniper Networks will maintain this release along with the life span of the underlying release. The service release number is after the R number; for example, 20.3R1-S2.12. Here, S2 represents the 2nd service release on top of 20.3R1 and is the 12th re-spin.

Junos OS Evolved Editions

Edition names show up in the installation package name between the release number string and the extension.

For Junos OS Evolved:

  • A null (empty) edition field denotes the standard image for Junos OS Evolved.

  • limited—Starting in Junos OS Evolved 20.3R1, limited packages are available. Limited packages do not have cryptographic support and are intended for countries in the Eurasian Customs Union (EACU). These countries have import restrictions on software containing data-plane encryption. An example of a limited package image for a PTX router is junos-evo-install-ptx-fixed-x86-64-20.4R1.17-EVO-limited.iso.