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The promise of software defined networking

John Dix | July 1, 2013
SDN is still an emerging technology. We take a look if it can live up to its promise of redefining networking.

If you aren't intimately familiar with software defined networking, don't fret. Only 10% of 450 IT practitioners at a recent Network World event raised their hands when asked if they understand SDN. But if the emerging technology lives up to its promise to redefine networking as we know it, there is no time like the present to dig in and learn more.

Proponents argue that, among other advances, SDN will centralize and simplify control of the network, make networks programmable and more agile, and create opportunities for policy-driven supervision and more automation. In short, SDN will help networks keep up with the speed of change made possible by the virtualization of other data center resources and provide the perfect complement to cloud computing.

But challenges remain. Many of the vendor cheerleaders, after all, are tiny startups. While the incumbents seem to have joined in the chanting, only time will tell if they are serious about change or simply paying lip service while working behind the scenes to scuttle advances so they can get back to business as usual.

That said, most industry pundits say the SDN movement has momentum now and, even though we're still in the early goings, there won't be any stopping this train. Now it is just a question of where we end up going, how long it takes to get there, and how different the coach looks when it finally arrives.

"There is a fundamental transition happening now because the status quo is not sustainable," says Nick Lippis, a longtime industry observer and co-founder of the Open Networking User Group (ONUG), an SDN user group he formed with Fidelity Investments. "The cost to operate networks is too high and growing too fast and you can't find enough people to manage these things anymore. It's time for change."

It's telling, for example, that the SDN movement is being led by users. The organization championing the cause is the Open Networking Foundation (ONF), whose board members include Microsoft, Yahoo, Facebook, Goldman Sachs, Google, Verizon and Deutsche Telecom.

Jim Metzler, vice president of consultancy Ashton Metzler & Associates, notes that standards bodies are typically staffed by vendors (usually grouped into three camps — those pushing the standard, those simply watching and those actively trying to slow down the effort), so the fact that SDN is being pushed by buyers greatly enhances its chance of success.

The magic
Broadly speaking, SDN makes change possible by separating the network control plane from the data plane, meaning control of the network is pried out of the devices that forward the packets and is centralized on a server called a controller. Rather than the classic approach of each network device principally worrying about adjacent devices and forwarding traffic based on that knowledge, centralizing intelligence makes it possible to see the network end-to-end and make smarter, big picture decisions, and when it comes time to make network changes, you can touch the network once instead of having to update each link in the chain.


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