Software-defined networking (SDN) is already one of the most hyped concepts in IT. Brent Lees, senior product marketing manager for EMEA of Riverbed Technology, looks at ways to start realising the promised benefits.

With agility increasingly seen as a key to business success, virtualised software applications and servers and cloud computing have emerged to support business agility. But businesses need more than this. They are quickly growing beyond the network “box”, or the limitations of the physical network infrastructure.

To overcome the rigidity of the traditional data centre network, software-defined networking (SDN) is emerging as one of the most hyped concepts in IT. The question is – can it deliver the necessary efficiency gains and productivity benefits, and how can these benefits be realised?

Introducing SDN to the network
Traditional network equipment bundles the decision-making logic (the “control plane”) and the data routing mechanism (the “forwarding plane”) into a single box. In SDN, these functions are separated. Boxes still move data, but the decisions are made by software running on general-purpose computers. SDN provides the fundamentals for effective network virtualisation.

Administrators are already familiar with the benefits of server virtualisation, which has streamlined workload management in organisations of all sizes. By deploying right-sized application-specific logical servers over a farm of inexpensive general-purpose physical server hardware, resource utilisation is increased and provisioning can be accomplished much more quickly.

Desktops soon followed. Rather than provision each machine and piece of software individually, IT soon discovered the advantages of centralising these processes and delivering them either through local servers, over the WAN, or even over the Internet.

SDN relies on well-defined application programming interfaces (APIs), which allow an organisation to develop specialised software that extends functionality beyond what is available out of the box. Load balancing, for example, no longer requires an expensive specialized appliance in an SDN environment, but can be handled with software and provisioned in a “service chain” along with other networking services such as firewalls.

These services run on commodity hardware that is sized (and can be resized) as appropriate. The underlying physical network is simplified, and redundant tools can be eliminated because resources can be moved around as needed.

Adjustments to the network can be made in real time through software applications, rather than having to frequently replace or reconfigure physical devices in the data centre. And SDN delivers the same benefits as other virtualisation initiatives, such as the ability to house logically separate entities on a single device, even if they have conflicting requirements that would ordinarily cause compatibility issues.

Virtualising the network
To varying degrees, network virtualisation isn’t new. Virtual LANs (VLANs) create logical local network segments across distinct physical network segments. Virtual switches manage the traffic between virtual machines, on either the same or separate physical hosts. But neither of these techniques can be considered full network virtualisation.

Administrators are beginning to consider whether it would be beneficial to bring full virtualisation to the network. For years this has been considered a legitimate possibility, but there have been concerns over managing state changes, access control lists, and counters in logical networks with thousands of virtual nodes.

SDN is proving to be good at solving these particular challenges, making it possible to build fully virtualised networks completely decoupled from the underlying hardware.

The end result: software-defined data centres
Data centres have enjoyed the benefits of compute and storage virtualisation for many years. SDN brings effective virtualisation to the network. The logical culmination of all these, then, is the software-defined data centre (SDDC).

The SDDC is characterised by broad programmability across all elements: compute, storage, and networking. Consumable services are decoupled from hardware and implemented as abstractions that, for all practical purposes, behave just like their old-fashioned physical counterparts. But they’re free from old-fashioned physical constraints.

The software-defined data centre delivers benefits in several important areas:

* Today’s applications are utilising more complex infrastructure requirements that can be a challenge to meet in order to ensure proper quality of service. The delicate balance of meeting each requirement without harming another process is improved by the level of abstraction made possible by the SDDC.

* Because resources are provisioned on demand, developers are free to focus on the business functionality of applications without undue concern about whether the network can respond—the network in an SDDC automatically reacts to changing application requirements.

* Combining a more consolidated and centralised control framework on top of commodity hardware means there are fewer specialised physical components that can break down and inhibit operations. In addition, centralised control brings improved visibility.

* With a reduced need for specialised network equipment, organisations employing an SDDC will likely see reduced capital and operational expenditures.

A fully software-defined data centre will be a game-changer for those organisations that successfully execute the vision. Just as cloud and big data have reached maturity and widespread deployment as part on an IT strategy, the SDDC is likely to define the corporate network in the years to come. Organisations should overlook the growing pains of the technology and start planning how and when to make the transition.