Open Network Linux (ONL) is an open-source, foundational platform software layer for next-generation, modular NOS architecture on open networking hardware.

Networking solutions based on ONL are delivering speed, freedom and economics and have now been adopted by hundreds of data center organizations, across hyperscalers, service providers, mainstream enterprises, and SaaS/cloud providers.

Bare Metal refers to the switches where the software and hardware are sold separately, that is, you can buy just the "bare metal". In other words, the end-user is free to load an operating system of their choice. ONL is an open source distribution of Linux for Bare Metal switches.

While ONL is based off of Debian Linux, it adds functionality specific to bare metal that's not included in existing traditional distributions. Relative to a standard server, bare metal switches have expanded infrastructure for their unique hardware including larger I2C buses, GPIO's, SFP's, LEDs, fans and temperature sensors.

Additionally, while many of these components are roughly standardized in the server world, for a variety of reasons, switch vendors do not always use the server-comparable components. As a result, ONL ships with a number of additional drivers to support this collection of hardware.

ONL includes a number of nicities that make working with a headless switch easier including network booting, cross-compilation workspace, overlayfs tricks to optimize flash writes, and a large collection of build utilities to leverage the ONIE install environment.

Open Network Linux supports multiple switch fabric APIs including: OF-DPA, OpenNSL and SAI.

Open Network Linux is compatible with most forwarding agents including: FRRouting, Quagga, BIRD, Facebook FBOSS, Google gNOS and Azure SONiC.

ONL is a base-level operating system and only includes example packet forwarding code. The main expectation is that you or other projects will write their own packet forwarding code.

ONL's goal is two fold:

First, to become a development platform for tinkers and DYI types to build their own forwarding applications.

Second to be a useful component for building full commercial solutions on top of bare metal switches. For example, Big Switch Network's SwitchLight OS is based on ONL.

As such, the expectation is that someone deploying ONL will build or deploy their own packet forwarding application on top.

Additionally, we expect that third parties will contribute binary-only forwarding applications as time goes on.

The best way to get involved is to look at the source code and subscribe to the mailing list