Junos OS Overview

Juniper Networks provides high-performance network devices that create a responsive and trusted environment for accelerating the deployment of services and applications over a single network. The Junos operating system (Junos OS) is the foundation of these high-performance networks. Unlike other complex, monolithic software architectures, Junos OS incorporates key design and developmental differences to deliver increased network availability, operational efficiency, and flexibility. These key advantages are:

• One operating system

• Concurrent software releases

• Modular software architecture

One Operating System

Unlike other network operating systems that share a common name but splinter into many different programs, Junos OS is a cohesive operating system that is supported across all devices and product lines. This enables Juniper Networks engineers to develop software features once and share the features across product lines simultaneously. Because features are common to a single source, generally these features are implemented the same way for all of the product lines, reducing the training required to learn different tools and methods for each product.

Concurrent Software Releases

Each new mainline version of Junos OS is released concurrently for all product lines. Each new Junos OS release includes working features released in previous versions of the software and must achieve zero critical regression errors. Any deprecated features or functions are not only announced, but any needed workarounds or solutions are provided. This discipline ensures reliable operations for the entire release.

Modular Software Architecture

Although individual architecture modules of Junos OS communicate through well-defined interfaces, each module runs in its own protected memory space, preventing one module from disrupting another. It also enables the independent restart of each module as necessary. This is in contrast to monolithic operating systems for which a malfunction in one module can ripple to other modules, possibly causing a full system crash or restart. This modular Junos OS architecture provides a high level of performance, high availability, security, and device scalability not found in other operating systems.

Generally, Junos OS is preinstalled on your Juniper Networks device when you receive it from the factory. When you first power on the device, all software starts automatically. You then configure the software so that the device can participate in your network. However, if needed, you can order Juniper Networks devices without any software installed, for additional flexibility.

You can upgrade the device software as new features are added or software problems are fixed. You obtain new software by downloading images from the Juniper Networks Support website onto your device or another system on your local network, then install the software upgrade on the device.

Juniper Networks devices run only binaries supplied by Juniper Networks. Each Junos OS image includes a digitally signed manifest of executables, which are registered with the system only if the signature can be validated. Junos OS will not execute any binary without a registered fingerprint. This feature protects the system against unauthorized software and activity that might compromise the integrity of your network devices.