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Turning to software to open up networks

Software-defined networking can scale better than traditional networking where control lies in firmware, but ubiquitous protocol still not available, say market players.
Written by Liau Yun Qing, Contributor

Software-defined networking promises scalability of services and faster data speeds, as control of networking flow is taken away from the firmware, says market players. However, they note that an industry standard has yet to be defined in this space.

David Krozier, principal analyst for network infrastructure at Ovum, said networks were evolving into a software-defined network (SDN) similar to how mobile networks were evolving to software-defined radio.

Ananda Rajagopal, senior director for product management and strategy at Brocade, explained that in software-defined networking, the forwarding function of a switch or router is controlled by software outside the device via an "open" interface.

"In contrast to traditional routers and switches, such software need not be embedded within the router or switch, and instead, runs on an external controller, for example, on a server," Rajagopal said. "Software-defined networks do this by separating the data plane--which is the forwarding plane--and control plane, and creating an abstraction layer."

He noted that a key benefit of software-defined networks for network administrators and operators was that the pace of innovation could be rapidly accelerated. "For example, a provider can develop a new application that requires changes to be done in the data flow without the need for a [networking] vendor to add such functionality into the switch or router," he said.

Krozier added that software-defined network has the potential to improve service velocity as new services can be readily deployed without the need to wait for firmware to be tweaked.

Networks also are more scalable as the abstraction layers allow the data plane and control plane to scale independently, he added.

Other benefits of software-defined networking include support for third-party applications with open network APIs (application programming interfaces) and service virtualization, where multiple applications can be supported on a single physical network, he added.

Mike Marcellin, vice president of product marketing and strategy, Juniper Networks, noted that software-defined networks could be useful in reducing the complexity of running heterogeneous networks.

However, he added that while software-defined networks might help reduce network complexity and improve control, the control software and protocols were not a replacement for the other elements.

Marcellin said: "Security, routing and energy management have been driven by a combination of silicon, hardware and software. In the industry's best implementations, these three components are optimized to work seamlessly together to drive the best outcome."

He noted that software-defined network as a term had been used increasingly by the Open Networking Foundation (ONF).

A non-profit consortium established in March 2011, ONF was foundedby Deutsche Telekom, Facebook, Google, Microsoft, Verizon and Yahoo, with the goal to "rethink networking" and "accelerate the delivery and use of SDN standards". Its members include Cisco Systems, Huawei, Juniper Networks, Tencent and Korea Telecom.

Standard protocol undecided
One protocol closely associated with SDN is OpenFlow.

The ONF, in particular, has been driving the protocol, noted Krozier, who explained how it enabled a software-defined network. "OpenFlow allows access to the forwarding table of an OpenFlow-compliant network element such as a switch or a router. By populating the forwarding table through the OpenFlow interface, a central controller-- rather than routing or switching protocols--can determine the path of a stream of packets [or data flow] that enter the network element," he said.

He added that OpenFlow does not define the rules used to handle data flows in a network element. Instead, it is a standard that defines a particular approach in communication rules to a network element.

However, at this point in time, it remains to be seen if the protocol will emerge the "ubiquitous choice" for connecting forwarding elements to controllers, Krozier said.

Networking giant Cisco, for one, believes OpenFlow is "more suitable for research and experimental purposes".

A company spokesperson told ZDNet Asia in an e-mail: "This technology is still in its infancy and is not pervasive in live production environments. Many industry groups and vendors are merely experimenting with software-defined network-related technologies."

He added that as part its software-defined networking strategy, Cisco will continue to provide support for numerous networking protocols which include OpenFlow.

Bringing network virtualization to cloud
According to Juniper Networks' Marcellin, SDN can benefit cloud computing by helping virtualize the network to allow cloud providers to manage the network holistically, instead of on a device-by-device basis.

Brocade's Rajagopal added that automation is needed needed in the age of a dynamic network. "The cloud era requires a dynamic networking infrastructure to be used where services can be delivered on-demand in order to meet the promise of elasticity," he said.

Here, a SDN can make changes to the data flow in a rapid fashion without the need for extensive human intervention, he noted, adding that this can cut down operational costs and accelerate time to revenue.

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