Software-defined Networking: creating dynamic, agile networks

by Stuart Hardy, Business Unit Manager of EOH’s Carrier and Network Solutions Division
The increasingly complex and dynamic nature of cloud computing, virtualisation and mobile services has placed new demands on networks. They must become more flexible and responsive, in order to adapt quickly enough to changes in the provisioning of the services that they carry. Software-defined Networking (SDN) is the new networking model that enables this.

What is Software-defined Networking?

Possibly the easiest way to understand SDN is to come at it from a virtualisation angle – specifically the concept of abstraction. Virtualisation, in essence, relies on abstracting hardware functions so that they can be controlled by software or programmed, rather than being dependent on and directly coupled to physical hardware.

Thus we see that server virtualisation allows any number of “virtual” servers to be created on a single physical machine using software, instead of each server having to be an actual physical machine, as was the case before virtualisation. The server systems and functions layer has been decoupled from the hardware layer.

Similarly, cloud computing implementations like Infrastructure as a Service use a form of virtualisation to dynamically provision IT infrastructure on demand. The physical infrastructure doesn’t have to be built each time – it is a virtual infrastructure that is provisioned programmatically, not physically. Once again, there is a decoupling of the functional and control layer from the physical layer.

The same principle is used to create SDN, which is something of a logical extension of these other forms of IT provisioning. The increasingly dynamic provisioning of IT infrastructure and services creates a demand for networks that are more flexible and responsive.

SDN is thus the decoupling of the network control layer from the hardware layer, allowing the network itself to be provisioned and controlled programmatically (virtually, so to speak), without a concomitant physical hardware provisioning requirement.

How does SDN change life for operators and organisations?

It’s not hard to immediately see how SDN changes things, not only for network operators, but for all organisations that have significant networking operations.

Less reliance on physical hardware

SDN removes the physical limitations of legacy networks. There is no longer a dependence on fixed hardware that also requires a fair amount of manual administration. For example, SDN switching and network controllers can be provisioned using software alone, rather than actual devices.

More flexible networks with faster provisioning

By decoupling function from physical hardware, SDN allows networks to be changed, expanded or contracted relatively instantaneously, compared to life without it. New network configurations and capabilities can be implemented using software only, where previously this would have required a lot of physical installation and configuration.

Significant networking cost savings

An obvious consequence of the above is that SDN significantly reduces the time and cost requirements of network installation, configuration and adaptation. Many of the processes that are traditionally executed manually can be automated, and less hardware expenditure is required. While big networking providers will see the most benefit from this, it also means less CAPEX for any organisation with a significant network.

More advanced cloud computing

Cloud computing is increasingly evolving towards the hybrid cloud model. These implementations often require sophisticated networking to integrate infrastructures, systems and data centres. SDN will make this quicker, easier and more efficient.

More intelligent networking

SDN can make networks more “intelligent” by allowing network logic to programmatically control network traffic management. This means better load balancing, more efficient content delivery, improved media transmission and better cloud services delivery.

Improved network security

SDN allows more granular security of all network components than is possible with more traditional fixed hardware networks. This is especially helpful with the proliferation of distributed apps and BYOD.

In short, SDN allows networks to be more versatile, responsive and adaptable, while reducing physical and human resource requirements, and costs. While it is not yet a mature technology, SDN is the dawn of truly agile, intelligent networking.


Stuart Hardy has been in the ICT industry since 1997, has been in the Telecommunications industry since 1997, intimately involved in product development, operations and product marketing roles. He has held Executive level positions in some of the largest Operators in South Africa and has founded and driven two successful start-up companies in the Mobile data and Wireless networking spaces. Today, Stuart is a Divisional Director for EOH in their Telecommunications sector.