Is software-defined networking (SDN) a solution looking for a problem to solve? Or is it the next revolution in the way that networks are designed, operated, and managed?

The answer depends on whom you ask and when you ask it. On one side of the debate are such thought leaders of the neophyte industry as Stanford University’s Martin Casado, the "father" of SDN. They are using SDN to solve complex networking issues. On the other side of the debate are networking-hardware incumbents like Dave Ward, CTO of engineering and chief architect at Cisco Systems. They see both the potential and the threat of SDN and are integrating SDN features into their existing portfolios of products and applications.

The opportunity offered by SDN is that by separating the logic of the control plane from the forwarding in the data plane, it will allow faster innovation as the networking hardware and software are allowed to evolve independently. Additionally, this decoupling allows a centralized high-level program to monitor and control the network’s behavior in a holistic fashion.

However, these opportunities come with challenges, such as scalability in control plane elements responsible for a vast number of routing and switching devices, as well as reliability as control plane elements fail or become compromised.

It is said that the full potential of compute virtualization cannot be realized until the network has the same flexibility and programmability required to support complex distributed on-demand applications. Instead of today’s monolithic vertically integrated hardware- and software-networking elements with a distributed topology database, SDN proposes a different networking model with horizontally integrated networking elements and a centralized topology database. The transition from vertically integrated hardware and software to horizontal integration of the computer industry in the 1980s led to the PC revolution. Now SDN can enable the same causality in the networking industry.

One of the most prominent SDN solutions to date revolves around network virtualization. In this case, the physical network is abstracted into a logical IP backplane where virtual networks are programmed and overlaid like virtual servers in the compute space. This particular implementation of SDN is solving a number of network operational issues, primarily in the large enterprise data center domain.

SDN is without question a new networking paradigm with the potential to change the fundamental laws of networking physics. At the end of the day, SDN will be what we, the networking industry, make of it. We at Cox look forward to exploring SDN solutions in our network as business drivers dictate.

— Bill Coward, Principal Architect, Cox Communications