programmable networks: the next big thing


If you didn’t know it already software-defined networking (SDN) is the next big thing in networking.  It’s similar to the virtualisation concept that has already impacted the desktop, applications and servers. The idea is that if you separate the underlying network hardware (the muscles) from the control functions (the brains), you can much more easily orchestrate services. In other words, you can manage your networks without having to unplug cables and move routers around.

SDN is essential in a cloud computing world were you may want to provision new cloud services speedily and flexibly. It’s also useful in data centers, campus networks, telco networks and mobile networks.

time to be flexible

The problems with the network protocols we use today are that they were developed decades ago and in isolation. They were never designed to interoperate and so, to control the router or switch, you have to open up the box. In addition, they also tend to be hierarchical, a design which made sense when client-server computing was dominant but is ill-suited to the new world of cloud computing, virtualisation, big data and mobile computing. 

And as IT has changed, so has our use of the network. And now it could be holding IT back.

  1. Lack of flexibility: when enterprises adopt a cloud computing, they need to be able to rapidly provision new connectivity to different locations. And with self-provisioning, they need to turn up or down, the computing, storage and networking resources simultaneously.
  2. Lack of scalability: those companies using big data analytics to mine through unimaginably large data sets are finding current networking topologies particularly restrictive as they constantly need to add huge amounts of network capacity to their data centre.
  3. Changing traffic patterns: as we move away from client-server computing and towards virtualisation, where applications and data reside on different servers, we’re creating bursts of east-west traffic before returning the packets to the users in a north-south configuration.  Also users want to access information from different devices, not just a desktop connected to a server.

According the Open Networking Foundation, an association of networking end-users, the big changes in IT that we have seen in the last five to ten years are demanding a new approach to networking.  It wants vendors to adopt the OpenFlow standard which “allows the path of network packets through the network of switches to be determined by software running on multiple routers. This separation of the control from the forwarding allows for more sophisticated traffic management than is feasible using access control lists (ACLs) and routing protocols.” OpenFlow is positioned as a Linux for networks (although many of the large vendors that signed up to it are deviating from the path.)

Even though there are a raft of SDN protocols (and therefore fragmentation), SDN is growing rapidly. A forecast by Plexxi, Lightspeed Venture Partners and SDNCEntral estimated that a $8 billion global market in 2015 will rocket to $35 billion in 2018. In fact, 40% of network spending in 2018 will be on SDN, they estimate. For more stats, check out this infographic.

as an enterprise, should I care about SDN?

There are number of benefits for enterprise that adopt SDN:

  1. Firstly, creating new networks will be as simple as setting up virtual machines.
  2. Secondly, IT managers will be able to administer all of their routers from a single controller.
  3. Thirdly, SDNs can give fine-grained security for applications, irrespective of device, which hard-wired networks can’t.
  4. Forth is lower capex as the routers and switches can be relegated to dumb muscle.
  5. And fifth, you save a lot of money on admin.

The network engineers who qualified to program command line interfaces (CLI) are expensive. In an SDN world, a controller (an orchestration tool) does away with the need for manual programming. The Najam Ahmad, director of network engineering at Facebook, one of the members of the ONF, said at a conference recently: "We feel it's [SDN] the way to build networks. ... CLI is dead, it's over," he said. "We want robots running the network and people building the robots."

So within an enterprise, SDNs could benefit the data center (allowing network virtualisation), campus networks (automated management of user profiles and application requirements) and improving the way they access cloud resources (rapid provisioning and flexible hand-off to cloud provider).

It’s still early days for SDN but we’re already seeing the network hardware giants Cisco, Juniper, Alcatel-Lucent, HP, Siena, Huawei and so on, jockey for position. Whether they agree on common standards for controllers is another thing.

For a good summary of how the SDN concept works, check out this InfoWorld slide show.


Photo credit: © kras99 -

Stewart Baines

I've been writing about technology for nearly 20 years, including editing industry magazines Connect and Communications International. In 2002 I co-founded Futurity Media with Anthony Plewes. My focus in Futurity Media is in emerging technologies, social media and future gazing. As a graduate of philosophy & science, I have studied futurology & foresight to the post-grad level.