Overview
Software-Defined Networking, or SDN, is a method of managing and controlling networks using software rather than relying only on physical hardware. It separates the network’s control plane (the decision-making logic) from the data plane (the actual traffic forwarding). This allows administrators to define how the network behaves through centralised software controllers.
What Problem Does It Solve?
Traditional networks are hardware-driven and complex to manage, especially at scale. Each switch or router must be configured individually, which slows down changes and increases the chance of errors. SDN solves this by providing centralised control, making it easier to automate tasks, enforce policies, and adapt to changing business or security needs.
How It Works
An SDN architecture usually has three layers:
- Application layer: Where business apps and policies define network requirements.
- Control layer: The SDN controller translates policies into instructions.
- Infrastructure layer: The physical or virtual switches and routers that forward traffic.
Communication between these layers happens through open APIs and standard protocols, such as OpenFlow. This makes networks more flexible and programmable.
Everyday Benefits
With SDN, organisations can roll out new applications faster, improve network security by applying policies centrally, and optimise performance dynamically. For example, bandwidth can be allocated to critical workloads during peak demand, or traffic can be rerouted instantly if a failure occurs.
Deployment Considerations
Adopting SDN requires investment in compatible controllers and network devices, as well as retraining teams to work with a software-driven approach. Most enterprises deploy SDN gradually, starting with data centres, cloud environments, or specific use cases like WAN optimisation and security automation.
