The concept of Software-Defined Networks (SDN) has been around for many years, but it has suddenly become a red-hot topic. Much has been claimed for SDN, and the number of competing voices has spread a certain amount of confusion about SDN, the role of OpenFlow and the Open Networking Foundation (ONF). This article sets out to answer some of the basic questions about SDN and what it can do for the enterprise.
The current media buzz around SDN really began in October last year with the first Open Networking Summit. This was the first public industry event exclusively dedicated to SDN and it was an immediate hit. The organisers had arranged seating for an 'optimistic' 350 delegates, but quickly had 600 applications to attend - a sign of just how much interest was already there.
The summit was jointly organised by Stanford University and the Open Network Foundation (ONF) - an organisation to promote SDN that had just been founded with members including Deutsche Telekom, Facebook, Google, Microsoft, Verizon and Yahoo, and expanding to 70 members within months. It is still growing, with a notable surge of interest in Europe at present.
The ONF and the mission of SDN
The inspiration for the ONF had its roots in academia, notably Stanford University, and a mission to evolve networking along lines not unlike the way that computing had evolved as a discipline.
The very earliest computing devices were logic machines hard wired to solve one specific problem, and the next step in electrical computing was to incorporate movable plugs to allow a certain amount of re-configuration of the hardware - so that one machine could be re-shaped to solve a range of calculations. But true computing began with the use of "software": instead of making manual changes to the hardware, instructions could be fed into a machine that would automatically configure its logical structure for the next task. The same machine that had been doing scientific calculations could now, in a few seconds, become a machine for doing the company accounts.
On the basis of this new, flexible infrastructure there evolved the concept of "higher level languages". The programmer writing software no longer needed to think in terms of configuring a logic array node by node for a new task, but could use familiar words like ADD, MULTIPLY etc to initiate standard operations. From there, computing has evolved to the point where anyone using software like MS Word can simply click on one icon and call up sophisticated processes, from spell-checks to auto-formatting and more.
In these terms, computing has come a long way, while its sister discipline, networking, lags way behind. Networks have hardly evolved beyond that second stage that relied on manual re-configuration.
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