Software-Defined Networking (SDN): What Is It?

SDN is getting a lot of hype at the moment. Coupled with its kissing cousin, network virtualization, it is all the buzz.

So what exactly is it?

At its most basic level, SDN is an approach to networking in which the control plane is decoupled from hardware and given over to a software controller.  

In a traditional network environment, when a packet enters a switch, rules in the firmware send the packet along the same path, treating all packets in the same way. Some enterprise switches are intelligent enough to recognize differing traffic types and can treat that traffic flow differently; however, such switches are expensive.

A central goal of SDN is to allow network engineers and network administrators to respond quickly to changing business needs without having to change underlying physical infrastructure or individual switches. Another goal is to allow the use of cheaper and dumber network hardware, dealing with the logic and control at a distributed software layer instead.

So what exactly does SDN mean to me?

Well, as a starter for ten, it means that if I have to buy any hardware off you to make it work, it is not SDN. The clue is in the title: “software-defined networking.” Like the hypervisor revolution of the early naughties, this means that hardware should be ubiquitous, with none defined by the vendor. Yes, you may have an HCL (hardware compatibility list), but you are not compelled to buy switch X from vendor Y; further, it matters not that you also have switch W from vendor Q in your environment, either.

So who are the players in this market?

This post will introduce the players in this market and will be continually updated as players enter or leave the space. Later posts will dig down further on the benefits and downsides of each particular product.