The most notable difference between SDN and traditional networking is that SDN is software-based while traditional networking is usually hardware-based. Because it’s software-based, SDN is more flexible, allowing users greater control and ease for managing resources virtually throughout the control plane.
Inversely, traditional networks use switches, routers and other physical infrastructure to create connections and run the network.
SDN controllers feature a northbound interface that communicates with APIs. Because of this communication, application developers can directly program the network, as opposed to using the protocols required by traditional networking.
SDN lets users use software to provision new devices instead of using physical infrastructure, so IT administrators can direct network paths and proactively arrange network services. Unlike traditional switches, SDN also has the ability to better communicate with devices using the network.
Virtualization epitomizes the primary difference between SDN and traditional networking. When SDN virtualizes your entire network, it generates an abstract copy of your physical network, and lets you provision resources from a centralized location.
Opposingly, with a traditional network the physical location of the control plane hinders an IT administrator’s ability to control the traffic flow.
With SDN, the control plane becomes software-based, allowing it to be accessed through a connected device. This access lets IT administrators manage traffic flow with greater detail from a centralized user interface (UI). This centralized location grants users greater control over how their networks work and how their networks are configured. The ability to quickly process different network configurations from a centralized UI is especially beneficial for network segmentation.
SDN became a popular alternative to traditional networking because it lets IT administrators provision resources and bandwidths as needed without requiring an investment of additional physical infrastructure. Traditional networking requires new hardware to increase its network capacity. The paradigm for SDN versus traditional networking could be distilled to the generalization: one requires more equipment for expansion and the other requires only keystrokes.