Let’s take a brief look at the two SDN controllers the market appears to be rallying around.
1. OpenDaylight (ODL)
The OpenDaylight project formed in 2013 as a consortium of vendors working openly to create a modular SDN controller. The effort is truly open source, where anyone willing to contribute useful code, documentation, or ideas is welcome to participate in the process using the forums of IRC, publicly accessible meetings, wikis, and so on to drive the project ahead.
ODL has enjoyed a great deal of early success, seeing a growing roster of vendors joining the ranks to contribute code and get involved in the governance process. ODL recently celebrated its second birthday, marking several key achievements along the way, including:
- 20 ODL user groups involving over 1,000 people
- Real-world deployments in a variety of organizations, including academia, telecom and government
- A growing consensus around YANG-based modeling, a standard (IETF) modular way of describing the configuration and state of a network device
- Sights set on policy, where a real-world business policy is translated into a network configuration
Regarding the latter, while most agree that programmatically defining the nebulous idea of policy is necessary to move network configuration ahead, policy is fraught with challenge. Taking a policy idea and translating it into a specific task requires a complex layer of abstraction over network devices with differing capabilities. How best to express intent? How best to abstract that intent? When a policy is defined, should the required configuration steps to meet that policy be specifically expressed, or instead be implied, allowing the device to determine for itself how to meet the requirements?
It’s a complex problem, but ODL is one of the major projects in the industry where policy discussions are happening. As a side note, OpenStack’s Congress project is another key open source project focused on policy. Cisco, too, has expressed its opinions on policy, submitting its OpFlex protocol to the open source community.
While some criticize ODL as involving “too many vendors and too few users,” the group has addressed the issue in part by creating an ODL Advisory Group. ODL’s Executive Director, Neela Jacques, describes the advisory group as, “a diverse group of the top thinkers, engineers and architects at leading financial, enterprise, telecom and cloud service providers.” The group will “provide guidance on roadmap, feature prioritization and use case development.” As with all ODL proceedings, Advisory Group calls happen out in the open for anyone to hear.
ODL has seen a steady stream of software updates, but release of only two major versions: Hydrogen in February 2014, and Helium in September 2014. The most current version is Helium-SR3 released in March 2015.
The project has momentum, new code is being developed and maintained, and a vast array of partners have committed support. But even more interesting is the fact that some vendors are using ODL as a base for their own controllers.
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