Cloud computing is spreading rapidly across the IT industry, and it's being heralded as the next IT revolution. While virtualization has been limited to servers and computers, a new form has begun to percolate in the troposphere: network virtualization. Network virtualization, or a software-defined network (SDN), allows users to switch the control of a network over to an operating system rather than hosting it on a data center, making the environment completely virtual. So what is SDN all about? And why do industry experts think it holds so much potential? Let's take a look at this emerging form of virtualization. (For background reading, see A Beginner's Guide to the Cloud: What It Means for Small Business.)

Software-Defined Network Defined

A software-defined network is a type of computing architecture whose main distinguishing factor is the separation of the data plane from the control plane in routers and switches. This means that control is implemented via software, rather than hardware, allowing a network administrator to manage network traffic from a central console. In cloud computing, this means a more flexible and efficient way to control traffic loads.

From a technical standpoint, SDNs encourage a more efficient way to operate a network environment. Networking, put simply, is the transfer of data from one server to another through routers and switches. There are faster ways to move across networks, and network routers dictate which avenue is fastest for certain packets of data. For instance, the fastest route for email is not necessarily the fastest route for video.

In a standard setup, a network administrator would need to set up and calibrate switches and routers manually. However, with an SDN, the administrator could adjust the switches' configuration from a management console running on an operating system, as well as create more virtual switches and routers as required.

From a capital expenditure angle, SDNs have the same cost savings, if not more, than virtual machines (VMs) running atop hypervisors. They allow for near-instantaneous scalability, while reducing energy and maintenance costs.

SDNs: Why They're Gaining Traction Now

While virtual networking through virtual local area networks (VLANS) and virtual private networks (VPNs) has been around for a while, SDNs have just recently started gaining traction thanks to the adoption of cloud computing.

The main difference between an SDN and what used to be referred to as a virtual network is the ability to scale. VLANs and VPNs allow for virtual networking, but not at the capacity needed to maintain a full-blown cloud environment. Why? Because they still suffer from the inflexibility of physical hardware. (Read more about VPNs in Virtual Private Network: The Branch Office Solution.)

With an SDN, you can still maintain VLANs and VPNs, but they have nearly unlimited potential. This works well when using a multitenant environment that runs on top of the cloud. VMs can be scaled along with the networking backbone needed to support them, while adjusting virtual switches for maximum efficiency.

What does this mean for my company?

We've already discussed the front-end benefits of an SDN. It allows for on-the-fly adaptation of switches and routers for end users. Where an SDN truly shines, however, is in the data center. In a data center, there are servers upon servers linked together. Depending on your environment, the number of servers could be in the thousands. (Learn more about data centers in 5 Essential Things That Keep a Data Center Running.)

The initial setup of any data center can be grueling. Most of the time, it takes some premiere planning in the hope that you will not have to reconfigure any cables. Anyone who has been tasked with cleaning up cables in a data center can tell you it’s a daunting task, but with an SDN, those fears are put aside.

Imagine a networking layer that allows you to make configurations and adjust how interconnected servers talk to each other on the fly. Cool, right? Now you can start to grasp the efficiency and power that an SDN can provide: instant scaling, efficient adjustments and easy adaptation. This, coupled with other cloud offerings, offers some interesting perspectives on the future of data centers.

What does this mean for the future?

SDNs provide another layer for the cloud computing stack. Connecting them with virtual storage and virtual machines allows for elastic resource allocation and true cloud performance. This means that your network will run just like an application, and all hardware will be located elsewhere. This idea is often referred to as a consolidated data center.

Another prospect for SDNs is an improved ability to load balance. Load balancing governs a data center's distribution of workload. Ideally, it manages network resources to achieve maximum throughput, minimize response time and avoid system overload. With an SDN, you gain the ability to properly load balance at the same time you may be experiencing network strain.

A major area where SDNs are being hyped is in the mobile sector, specifically service providers. As of now, building a network takes a rigorous amount of planning. Carriers have to think of where people will be, where populations will grow and potentially where customers will not be in the future. With the functionality of an SDN, the service provided is no longer static, but elastic, allowing for savings in terms of infrastructure needs and the costs of large-scale planning.

SDNs in a Nutshell

SDNs provide a huge advantage to networks both big and small. Having the ability to instantly scale and adjust network speed, settings and resources allows for true cloud performance when paired with other cloud offerings such as virtual machines and virtual storage. Along with the ability to scale for end users, SDNs allow for data center consolidation. This, in effect, reduces maintenance and energy costs, allowing IT departments to focus less on infrastructure and more on what really drives business: strategy.