In reality, the hype behind software-defined networking (SDN) started roughly a year ago with the creation of the Open Network Foundation (ONF), founded by Deutsche Telekom, Facebook, Google, Microsoft, Verizon, and Yahoo as a non-profit organization. The goal was to rethink networking, and quickly bring to market standards and solutions.
ONF is promoting the OpenFlow communications protocol as the heart of a SDN. OpenFlow was released as an industry standard at Interop Las Vegas 2011, and has since found its way into many vendors’ physical Ethernet routers and switches, virtual switches and access points. Development of the OpenFlow standard is now managed by the ONF.
What makes SDN Important?
In a software-defined network, switches and routers take some form of direction from a centralized software management element. In the context of OpenFlow, the control plane is abstracted from the data forwarding plane. A centralized controller, which maintains a real-time, holistic view of the network, defines network paths as "flows" and distributes this flow data to individual switches and routers. With these flows, the controller coordinates the forwarding of data across all network devices, enabling the automation and granularly managed dynamic provisioning necessary in virtualized environments and cloud networks.
SDN is certainly maturing, notes Eric Hanselman, research director for networks at The 451 Group. "People are actually starting to apply software-defined networking broadly, and OpenFlow [specifically], to solve some real-world problems," he says. "There are real applications where SDN provides some specific benefit.”
The Near Term
In a speech given at the October 2011 Open Networking Summit at Stanford University, Jonathan Heiliger, who helped found ONF and recently resigned as Facebook's VP of technical operations, said that the migration toward software-defined networks will move faster than carriers' migration to IP in the late 1990s. He claims that vendors and network administrators are starting to embrace SDN, driven by the need for network operators to have more control over their infrastructures and be able to customize them more for their own needs.
Heilgler thinks that just as the telecommunications industry once moved to IP from specialized systems such as ATM (Asynchronous Transfer Mode), it will adopt SDN in place of unique network architectures for each vendor. Adopting a common standard for SDN will help vendors to compete, just as IP did, but it will also help carriers deploy new services and even allow their enterprise customers to implement services between their own sites over the carrier network, he said.
Because of those motivations, the migration to SDN will take less time than the gradual move to IP, which took several years, Heiliger said. But it won't begin for another 18 to 24 months, he added. The entire software stack for SDN needs to mature first, he said.