junos

Junos OS, commonly referred to as Junos, is Juniper Networks' network operating system for its routing, switching, and security devices. It provides a single, unified software platform across hardware families, emphasizing reliability, security, and ease of automation. Junos OS is built on a BSD-derived kernel and uses a modular architecture in which most functions run in separate user-space processes.

In Junos, the control plane runs on routing engines while the forwarding plane operates on packet forwarding engines. This separation enables rapid failover and non-disruptive maintenance. The software ships as a single image per device and maintains a consistent CLI and configuration model across platforms. Configuration is hierarchical and transaction-based: administrators edit a candidate configuration, then issue commit to apply changes; rollback and rollback to previous versions provide configuration safety. Features such as commit-confirm, non-stop routing (NSR), and graceful routing engine switchover (GRES) support high availability.

Junos supports standard routing protocols (BGP, OSPF, IS-IS, RIP), MPLS, VPNs, QoS, firewall filtering, NAT, and VRFs, along with secure management and automation capabilities. Management interfaces include a CLI, NETCONF, and REST APIs, with automation options via tools and libraries such as PyEZ for Python. Junos Space offers centralized management and analytics for large deployments.

First released in the late 1990s, Junos OS is widely used in service providers and enterprises for core routing, edge devices, data centers, and security gateways due to its consistency, robust feature set, and strong change-control model.