The OpenDaylight project [1], founded in April 2013, is a "community-led, open, industry-supported framework for accelerating adoption, fostering new innovation, reducing risk, and creating a more transparent approach to Software-Defined Networking" (SDN). OpenDaylight operates under the auspices of the Linux Foundation and has the support of major players in the networking industry: Brocade, Cisco, Juniper, and Citrix are in the front row, along with Red Hat, IBM, and Microsoft. The project aims to create a foundation on which the members will then build their SDN products. The code is mainly written in Java and Python and is licensed under the Eclipse Public License (EPL) 1.0.

The first tangible result of the collaboration is the Hydrogen release from February 2014. Hydrogen is actually a complete SDN software distribution, because OpenDaylight consists of numerous subprojects that develop individual components. Synchronized semi-annual releases are planned to ensure consistency.

At the core of OpenDaylight is the SDN controller. Its components share a Java Runtime and communicate with each other via function calls. Below this control layer is the southbound interface (as shown in Figure 1), where everything that is more tangible than the control plane resides.

[...]