Software-defined networking — the journey starts now

At this year’s Gartner symposium in Barcelona, everyone was talking about software-defined networking (SDN) and how it promises to revolutionise the way IT works. Virtualisation and cloud technology have already transformed the way we provision compute and storage. But what we find now is that the network is still very rigid, inflexible and entirely dependent on human intervention.

SDN represents the decoupling of the control plane from the data plane, This is important because it allows the whole network to be controlled from a single point. The key benefit of this approach is a step change in agility, which will allow organisations to respond to business demands in next to no time - all but cutting out human input could reduce provisioning times from weeks to minutes.

Although the SDN story is still very much in its infancy, we can see four clear stages ahead:
• Network automation — at present, software control of our networks is achieved in proprietary and often rudimentary ways. Only by opening up the application programming interfaces (APIs) will we start to achieve the agility we need.
• Network virtualisation — once we have basic automation in place, the process of separating the layer 2/3 network from the physical layer can truly begin. Although the technology is still taking shape, we see a lot of potential in software-based controllers using OpenFlow, the new SDN protocol, to program virtual switchers inside software hypervisors – often referred to as overlay.
• Extending SDN to the WAN — it’s not just data centres that will benefit, there’s no reason why SDN can’t also drive our WANs.
• True software-defined networking — ultimately, the goal has to be a simplified physical layer operating OpenFlow only, with standardised APIs to optimise the way we consume network resources. While operators and their customers have everything to gain, vendors are naturally cautious and we need to recognise that there will be some resistance — and work to overcome it.

Switch-based or overlay?

When Gartner VP, Neil Rickard, addressed the symposium , he revealed that there is an installed base of non-SDN-compatible equipment worth over $40-billion out there, which builds a strong case for the overlay approach we’re implementing at Colt.

Starting with our data centres, we’re introducing SDN at the edge. We’re evaluating switches that support OpenFlow, and using our experiences to influence the work of Internet Engineering Task Force (IETF) and Open Networking Foundation (ONF). As operators who will be using the new technology, it’s really important to ensure that the evolving standards deliver a simple, vendor-independent physical layer that works.

Organisational impact

This decoupling of the OSI layers requires a similar rethink when it comes to organisational structure. This will be a major challenge for all IT-based organisations. At Colt we reorganised to ensure we have the right skills in the right place, with clear communication lines to ensure that everyone - whether from a network or IT background - is working towards a common goal.

What’s clear is that this process is anything but simple, but the reward makes it extremely worthwhile. This journey is just starting, and we’re looking forward to mapping out the route alongside our customers.