The benefits of software-defined networking (SDN) in operator networks have been well documented and include the simplification of ageing and complex networks as well as ease of customization of the network services. This much is now well understood, but what is less is understood is what can be built and improved when SDN gear is deployed in the network.

The most exciting opportunities for SDN are in the applications that can be built upon its framework. It's a situation similar to the opportunity enabled by the launch of consumer app stores for mobile devices. With app stores in place, developers have been able to let their imaginations run wild to develop applications that suit every taste and interest. What app stores did for smartphones, SDN will do for networking gear. In an SDN-enabled network, service providers can create any number of applications that can cut their opex and capex, improve customer experience, and deliver new monetization opportunities.

At the start, not all of the SDN applications will be completely new. A lot of them will actually be replicating or improving upon the applications that are currently running on routers and switches. In most cases, these applications are going to be developed by the network infrastructure vendors themselves, to provide feature parity with their legacy routing and switching gear.

It is the stage beyond this where it starts to get really interesting. To explore the potential of SDN applications for service providers, let us take the theme of application-aware routing and follow it through to the value-added services that it enables. Application-aware routing applications will enable routing decisions based on application-level insights and characteristics. An SDN architecture eliminates the need for a dedicated Layer 7 request router in a service-provider network. Application-aware routing applications provide granular control over application-level characteristics and allow service providers to influence the quality of experience for subscribers based on network conditions.

Additionally, service providers currently size their networks for peak utilization, resulting in unused bandwidth. However, Layer 7-aware SDN applications help operators save costs on their networks by ensuring all bandwidth is utilized by sizing the network depending on the network conditions. Here are three major areas where Layer 7-aware SDN applications can deliver benefits to network operators and their customers.

In a service-provider edge network, there will be content servers used for media caching or delivery. These are deployed by the operator or by content delivery network (CDN) service providers. Content to be served to the users is prepopulated and distributed across multiple content servers and, in some cases, across multiple geographies. SDN apps built to handle content availability will be able to provision flows in the network based on the type and availability of the content. Before routing requests to servers, SDN applications can check the availability of the content in the content servers. A content-routing SDN application will enable discovery of content in the content servers and provide intelligence on its availability. This intelligence can be used to route requests to the correct server where the content resides. Therefore, SDN applications will be able to route requests from web sites that generate dynamic content, which are non-cacheable, to a server providing dynamic content rather than a caching server, greatly reducing network latency.

SDN applications will also be able to monitor the availability of network services across the entire network before routing data. Traditionally, network monitoring services only check the availability of Layer 2 or Layer 3 paths. However, in the instance of the content-delivering application being down, this would not be picked up when monitoring only Layer 2 and Layer 3 paths. Using SDN applications, content routing can be designed to perform service-availability checks before provisioning flows to the network switches.

Through SDN applications, operators can use bandwidth management to ensure end users receive optimal browsing and online video watching experiences. These SDN applications can monitor the bandwidth requirements then provision user flows to match the bandwidth and latency requirements of the Layer 7 application. This application-aware approach to bandwidth management will ensure a better user experience through better video playback with zero buffering.

There is little doubt at this stage in the game that SDN is becoming a reality in operator networks. However, beyond the immediate impact of simpler management of the network, it is the SDN applications that will really bring powerful improvements to operator’s network and business. That is why network infrastructure providers, in particular, need to start mapping out this future to harness all the potential that SDN can provide. By thinking ahead and acting on SDN applications now, network infrastructure providers and operators will be able to rapidly evolve to provide customized, flexible networks that can radically enhance the end user experience — and their own bottom lines.