Defining Software-Defined Networking


We’ve long heard about the benefits of Software-Defined Networking (SDN) for cloud service providers and in data center architectures.  Today, however, the SDN architecture model is expanding rapidly in the enterprise market, as well as to companies looking for a network framework that allows for greater automated provisioning, network virtualization, and network programmability. Essentially, SDN enables network administrators to manage network services from a control plane on a centralized controller by virtualizing the physical network. Enterprises can model the physical network environment into a software environment, which in turn helps to streamline administration and to reduce complexity. This is because software can automate many network administration tasks once done manually. In a cloud environment, this is extremely helpful because administrators can scale quickly to support hundreds of servers and thousands of workloads.

SDN is a more efficient and flexible way to manage networks and traffic loads, including those in virtualized environments, because administrators can leverage more efficient and cost-optimal, commodity switches for some data. With this level of granular control, it’s no surprise that IDC predicts strong growth in the SDN market for years to come. In fact, a recent report shows the worldwide SDN market is expected to grow to $12.5 billion by 2020 (Source: Business Wire). Let’s examine two important characteristics of SDN, including:


  • Centralized control- In a software-defined network, a centralized controller serves as a single point of configuration and it has complete control over all network paths and device capabilities. The controller translates business policy directly to network device-level policy to help enforce consistency across the network. That means that data plane behavior- including rules for packet handling and designating different network paths for different traffic types- is managed centrally. This is compared to traditional network architectures where control plane protocols don’t have visibility into the applications running over the network, or how the network may affect performance. Through this model, an SDN architecture has more direct control over how it moves specific packets and it can adapt to changing network conditions quickly, while also ‘micromanaging’ traffic flow. Automated provisioning and configuration with SDN architectures also allow for more rapid deployment of applications and services.  



  • Network programmability- The ability of the SDN to provide full programmability of the entire network from a single location allows for greater network automation. In this architecture, an SDN controller relays information to the forwarding plane of network devices (switches and routers, both physical and virtual) using southbound APIs. And, it relays application and business logic via northbound APIs. Two leading SDN communication protocols used in these environments are OpenFlow (OF) and OpFlex (used by Cisco’s ACI platform).  These protocols help switches ‘communicate’ with a variety of vendor platforms and devices. Using a common application interface allows users to integrate heterogeneous switches into a single SDN controller. Then, the SDN controller can ‘talk’ directly with network devices to adapt to changing business requirements. Many believe protocol standards are the key to secure programmable networks of the future. Through these interfaces, network administrators can better partition traffic, control data flow for optimal performance and manage new configurations and applications.



If your organization is managing a virtualized infrastructure, a multi-tenant cloud-computing architecture, or a platform that requires real-time analysis and adaptability, an SDN architecture offers many advantages. Software-defined networks allow for more centralized intelligence and control over network traffic flow, including simplified provisioning, optimized performance, and granular policy management.


Leave a Reply

Your email address will not be published. Required fields are marked *