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. [break]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 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’ and ‘MULTIPLY’ 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.
Let us say you have a fundamental idea that could accelerate your corporate network – how could you test it? Here is an example: one student at Stanford wanted to experiment with load balancing. Load balancers usually direct traffic to the server with the lightest load, regardless of how congested the traffic to that server. What would happen if the balancer also took the traffic into account?
In theory this is a very simple experiment, but would anyone dare try it out on a large working network? Just think of the labour, the potential disruption during set-up and consequent risk that the experiment might unbalance such a complex system and lead to unforeseen consequences – with so many users relying on the service.
In fact, this experiment was actually carried out, first on Stanford’s own network and then nationwide on the GENI test network. Professor Nick McKeown, speaking at the 2011 Open Networking Summit put it like this: “For the first time I’ve seen a graduate student able to take an idea and run it on a national network”.
The reason that this was allowable was that Stanford was pioneering a new approach to SDN, based on a standard now named OpenFlow.
OpenFlow
OpenFlow began in Stanford University, with version 1.1.0 released in February 2011, and was first demonstrated at InterOpNet Lab in May 2011. And Professor McKeown is the man behind the creation of OpenFlow – an industry-standard protocol that allows network operators to reprogram a network’s control plane from a central interface. Instead of having to go into the physical network and tweak masses of boxes, general instructions can be sent out across the entire network, or subsections of the network – just as the introduction of software made it possible to automatically configure a computer for different purposes, without having to manually alter its structure. This makes the network into “a software-defined network”.
Whereas in a normal router or switch the fast packet forwarding (data path) and the high-level routing decisions (control path) happen in the same device, with OpenFlow these two functions are separated: the datapath still resides on the switch, while the high-level routing decisions are moved to a separate controller. The open flow switch and controller communicate via the OpenFlow protocol.
In this regard, OpenFlow has the potential to become the “Android of networking” – an open standard that will encourage an open marketplace of new SDN applications to meet every networking need and business pressure.
Today’s drivers for SDN in the enterprise
It is hardly necessary to spell out for the enterprise IT readership the many business, economic and social pressures now impacting their already demanding roles. Enough has already been written about the complexity, management and security problems caused by the transition from yesterday’s closed, plug in network to today’s permeable wireless-enabled networks linking a shifting population of mobile users with many of their own personal devices on the network.
There are the pressures of increasing virtualization, of reliance on video and other bandwidth-hungry applications, of new threats to data security and government legislation over privacy laws and border control of data.
The point is that replacing the brick-by-brick hardware management of a network with central software control system opens up a whole new world of opportunities for the IT department. With global visibility and control you can dynamically provision the network and make it more elastic and optimize the use of resources.
SDN traffic management allows network virtualization and can help support cloud services, including hybrid cloud computing. Service-aware routing can streamline delivery of video and other lengthy traffic flows according to a user’s profile, the congestion state of network, and other parameters. SDN permits scalable, granular bandwidth allocation: you can use SDN to program the right access, security, QoS, and other policies along with the pipelines for each flow to offer high-level services, or an optimal user experience, without having to configure a whole lot of boxes along the path.
A user could switch between chatting on their smart phone, watching a video, and streaming music without any service degradation. Videoconferences and interactive traffic can be sent down paths engineered for optimal experience while other traffic is routed normally.
The question is not whether SDN has any relevance for enterprise networking, but rather: what is the best way to find out more? Even if your company is not yet in dire need of this technology, SDN will be playing an increasing role in maintaining competitiveness.
A more nimble network will help your business outpace the competition – don’t be left behind.
Ghosh is VP, Asia Pacific & Japan, Extreme Networks
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