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February 4, 2014

What is Software Defined Networking (SDN)?

CBR guides you through a 101 on SDN; should your business use it?

By Ben Sullivan


SDN, or Software Defined Networking, is a layer of software that sits between physical network components and the network administrators who configure them. This layer of software allows the administrators to control the network devices through a software interface instead of having to manually configure hardware through physical processes. Think of it as traffic lights for the network, rather than a person standing up with a stop and go sign.

How does it work?

Delving a little deeper, there are two ‘planes’ on network devices: a control plane that chooses where traffic is sent and a data plane that forwards the traffic depending on where the control plane tells it to go. SDN has detached these two planes, with the data plane remains with the hardware, but the control plane (the one that chooses where the traffic is going) is now controlled via software, meaning that administrators no longer have to execute all command and control rules on the hardware itself.

With this ‘decoupling’, network administrators can control network traffic from a network console, allowing them to change data traffic rules on a case-by-case basis, allowing organisations to decrease their reliance on more expensive switches that must be set manually on the hardware.

As SDN is an open-source product, and thus vendor-neutral, it can operate within any vendor’s network hardware. This gives firms the ability to avoid vendor lock-in, and increases agility, as the task of connecting up to different clouds, apps, and network devices becomes simplified; it’s all controlled via a software interface that has replaced the need for administrators to do it manually.

The future of SDN

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All the big names have adopted SDN: Cisco, IBM, Juniper Networks, Citrix, Dell, Google and more. It’s predicted that with this much investment, SDN will assume a role in IT infrastructure at some point in the near future.

What’s stopping that now is the confusion IT decision makers are having in the uses for SDN. Much like cloud when it first appeared, some enterprises cannot see how SDN will save costs and improve overall network operations. However, as IT project timeframes decrease, and the need for greater virtualisation increases, SDN will drive IT to adopt it as a more efficient way of configuring networks.

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