OpenFlow originated in academia, from research work conducted at Stanford University and the University of California, Berkeley. Academics remain intensively involved in the development of OpenFlow, but the protocol, a manifestation of software-defined networking (SDN), appears destined for potentially widespread commercial deployment, first at major data centers and cloud service providers, and perhaps later at enterprises of various shapes and sizes.
Encompassing a set of APIs, OpenFlow enables programmability and control of flow tables in routers and switches. Today’s switches combine network-control functions (control plane) and packet processing and forwarding functions (data plane). OpenFlow aims to separate the two, abstracting flow manipulation and control from the underlying switch hardware. thus making it possible to define flows and determine what paths they take through a network.
From Academic Origins to Commercial Data Centers
Getting back to the academics, they wanted to use OpenFlow as a means of making networks more amenable to experimentation and innovation. The law of unintended consequences intervened, however, and OpenFlow is spreading in many different directions, spawning a growing number of applications.
To see where (or, at least, by whom) OpenFlow will be applied first commercially, consider the composition of the board of directors of the Open Networking Foundation (ONF), which bills itself as “a nonprofit organization dedicated to promoting a new approach to networking called Software-Defined Networking (SDN). SDN allows owners and operators of networks to control and manage their networks to best serve their users’ needs. ONF’s first priority is to develop and use the OpenFlow protocol. Through simplified hardware and network management, OpenFlow seeks to increase network functionality while lowering the cost associated with operating networks.”
The six board members at ONF are Deutsche Telekom, Facebook, Google, Microsoft, Verizon, and Yahoo. As I’ve noted previously, what they have in common are large, heavily virtualized data centers. They’re all presumably looking for ways to run them more efficiently, with the network having become one of their biggest inhibitor to data-center scaling. While servers and storage have been virtualized and have become more dynamic and programmable, networks lag behind, not keeping pace with new requirements but still accounting for a large share of capital and operational expenditures.
Problem Shrieking for a Solution
That, my friends, is a problem shrieking for a solution. While academia hatched OpenFlow, there’s nothing academic about the data-center pain that the six board members of the ONF are feeling. They need their network infrastructure to become more dynamic, flexible, and functional, and they also want to lower their network operating costs.
The economic and operational impetus for change is considerable. The networking industry, at least the portion of it that wants to serve the demographic profile represented by the board members of ONF, must sit up and take notice. And if you look at the growing vendor membership of the ONF, the networking industry is paying attention.
One of many questions I have relates to how badly Cisco and, to a less extent, Juniper Networks — proponents of proprietary alternatives to some of the problems SDN and OpenFlow are intended to address — might be affected by an OpenFlow wave.
Two Schools of Thought
There are at least two schools of thought on the topic. One school, inhabited by more than a few market analysts, says that OpenFlow will hasten and intensify the commoditization of networking gear, as a growing percentage of switches will be made to serve as simple packet-forwarding boxes. Another learned quarter contends that, just as the ONF charter says, the focus and the impact will be primarily on network-related operating costs, and not so much on capital costs. In other words, OpenFlow — even if it is wildly popular — leaves plenty of room for continued switch differentiation, and thus for margin erosion to be at least somewhat mitigated.
The long-term implications of OpenFlow are difficult to predict. Prophecy is made more daunting by OpenFlow hype and disinformation, disseminated by the protocol’s proponents and detractors, respectively. It does have the feeling of something big, though, and I’ve been spending increasing amounts of time trying to get my limited gray matter around it.
Look for further zigzagging peregrinations on my journey toward OpenFlow understanding.