NOSIX: A Portable Switch Interface for the Network Operating System

Even with the success of software defined networks (SDN), it remains challenging to write a portable, correct, and efficient controller application. This is due to the mismatch between the expectations of controller applications and (i) the heterogeneity of switches and (ii) the primitives offered by OpenFlow, the prevalent SDN protocol. We introduce NOSIX, a portable low level switch programming API. Like its OS name cousin, it facilitates the development of portable low level applications (i.e., applications that directly built on the flow model) and at the same time serves as a building block for higher abstraction frameworks [12, 10]. Designed to be a minimalistic model, NOSIX purposefully only targets one switch as a time, leaving network wide consistency, topology and distribution to higher layers. It provides applications with a view of virtual flow tables without re source or feature constraints, while supporting consistent and efficient rule updates and counter collection. Underneath NOSIX, vendor defined switch drivers synchronize the virtual flow tables with the physical tables on the switch, and thus hide heterogeneity and enable switch specific optimization.