ONOS Open Network Operating System

ONOS (Open Network Operating System) is an open-source software platform designed to provide a flexible and scalable operating system for software-defined networking (SDN) environments. It is built on top of the OpenFlow protocol, which allows for centralized control and programmability of network devices. ONOS aims to enable the development of innovative network applications and services while providing a high level of scalability, performance, and reliability.

The motivation behind ONOS stems from the need for more dynamic and programmable networks to meet the evolving requirements of modern applications and services. Traditional networking architectures often lack the agility and flexibility to adapt to changing network conditions, leading to suboptimal performance and limited innovation. SDN emerged as a solution to address these limitations by separating the control plane from the data plane and centralizing network control and management.

ONOS acts as the brain of an SDN infrastructure, providing a unified control plane that manages network devices and facilitates communication between them. It enables network operators to dynamically control and program their networks using high-level abstractions and APIs, simplifying the development and deployment of network applications. With ONOS, network operators can define network policies, configure network behavior, and monitor network performance in a centralized manner.

One of the key features of ONOS is its scalability. It is designed to handle large-scale networks with thousands of devices and millions of flows. ONOS achieves scalability through a distributed architecture that allows it to run on a cluster of commodity servers, distributing the control plane tasks across the cluster nodes. This distributed approach ensures that the system can scale horizontally by adding more nodes to the cluster as the network grows.

ONOS provides a modular and extensible architecture, allowing developers to add new functionalities and customize the behavior of the system. The core of ONOS provides essential services such as device drivers, network topology management, and flow management. Additional functionalities can be added through a plugin architecture, which enables the integration of new protocols, network services, and applications. This modular design promotes collaboration and innovation by allowing the community to contribute and share new features and enhancements.

To enable the development of network applications, ONOS offers a rich set of programming abstractions and APIs. The northbound APIs allow applications to interact with the control plane and request network services, such as traffic engineering, load balancing, or security policies. ONOS supports multiple programming models, including a reactive model based on event-driven programming and a proactive model based on the construction and installation of flow rules.

ONOS also provides southbound APIs to communicate with network devices and control their behavior. The most common southbound interface supported by ONOS is OpenFlow, a protocol that enables the centralized control of switches and routers. However, ONOS is not limited to OpenFlow and can support other protocols, such as NETCONF or P4, through additional plugins.

The ONOS community actively contributes to the development and improvement of the platform. It is an open-source project hosted by the Linux Foundation, and it encourages collaboration and participation from industry and academia. The community follows a transparent and inclusive development process, allowing anyone to contribute code, report issues, or propose enhancements. Regular releases and updates ensure that ONOS remains a reliable and up-to-date platform for SDN deployments.

In addition to its core capabilities, ONOS has been integrated with other open-source projects to provide a comprehensive SDN solution. For example, ONOS can be combined with the OpenStack cloud platform to enable the orchestration of network resources in a cloud environment. Integration with the CORD (Central Office Re-architected as a Datacenter) project allows ONOS to be used in the context of Central Offices (COs) transformation into agile and programmable data centers.

In summary, ONOS is an open-source operating system designed for software-defined networking. It provides a scalable and flexible platform for controlling and managing network devices, enabling the development of innovative network applications. With its modular architecture, rich programming abstractions, and support for multiple protocols, ONOS offers a powerful tool for network operators to realize the full potential of SDN in their environments.