Junos Command-Line Interface (CLI) Commands Modes - dummies

Junos Command-Line Interface (CLI) Commands Modes

By Walter J. Goralski, Cathy Gadecki, Michael Bushong

A fundamental trait to understand about Junos OS is that it separates the command-line interface (CLI) commands into two modes called the operational mode and the configuration mode. The former is used for monitoring tasks. The latter is used for configuring a device and network.

  • Operational mode: A set of commands to manage and monitor device operations. For example, you can monitor the status of the hardware and software and perform maintenance tasks, such as upgrading software or managing device files.

  • Configuration mode: A set of commands to set up the device and the network. For example, you can configure user access, the system properties, and the device’s interfaces, protocols, and services.

The Junos CLI further structures the activities of each mode into a set of hierarchies. The hierarchy of each mode is made up of cascading branches of related functions commonly used together where deeper levels are more and more specific.

The structured hierarchy of the CLI brings practical elegance, and it’s a favorite trait of long-time Junos users. By logically grouping activities, the Junos CLI provides a familiar, consistent structure for knowing where you are, finding what you want, moving around the interface, and entering commands.

Also, when you are setting up a configuration for a particular aspect of the network, such as its protocols, or verifying or troubleshooting the network, everything is in the same place.


The convenient hierarchical structure of Junos means that you don’t waste a lot of time scrolling through the entire configuration every time you need to make a change. You simply navigate your way to the necessary area of the command tree.