ONOS

ONOS, the Open Network Operating System, is an open-source distributed software-defined networking (SDN) controller platform designed for large-scale networks such as service providers and expansive campus deployments. It provides a highly available, scalable control plane capable of managing thousands of devices across multiple sites. ONOS emphasizes a distributed core where state and decision-making are shared among cluster nodes, enabling fault tolerance, rapid failover, and consistent network-wide policy.

The project originated at ON.Lab and is stewarded by the Open Networking Foundation. It is released under the Apache 2.0 license and maintained by a global community of developers, vendors, and researchers. ONOS aims to support real-world carrier-grade needs while promoting an open, extensible ecosystem for network applications.

Architecture and features: ONOS features a modular architecture built around a distributed core, a flexible service layer for applications, and a set of southbound adapters that connect to network devices. It supports multiple southbound protocols, including OpenFlow and NETCONF/RESTCONF, enabling operators to manage diverse equipment. The platform provides comprehensive northbound interfaces, including REST APIs and Java APIs, to facilitate automation and integration with orchestration systems. A key component is the Intent framework, which allows operators to express high-level policies (e.g., connect A to B with specific constraints) that ONOS translates into device-level configurations. Built-in applications cover routing, high availability, traffic engineering, and policy enforcement, and the framework allows third-party apps to extend functionality without modifying the core.

Deployment and impact: ONOS is used in academic research, carrier-grade networks, and large-scale campus deployments. Its distributed, multi-tenant design and extensibility make it suitable for experimental environments as well as production trials.