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Software-defined networking (SDN) vs traditional networking explained

What is SDN?

Software-defined networking (SDN) is characterized as “the decoupling of control and packet forwarding planes in the network”.1 SDN allows networks to connect to apps using application programming interfaces (APIs). This relationship between SDN and APIs supports application performance and security and helps create scalable, dynamic network architecture.

SDN is frequently used for application deployment by enterprises globally and helps these organizations to quickly deploy their applications while simultaneously reducing the costs for deployment and operating. SDN helps IT administrators provision and manage their network services from a centralized point.

Yielding network resource optimization, programmatic management and control, SDN uses open APIs to support and maintain network control. This network control is created when SDN decouples the network configuration and traffic engineering, severing them from their fundamental hardware infrastructure. This separating action allows for OpenFlow use and the use of more open protocols, which can access network switches and routers that frequently use proprietary and closed firmware. These open protocols often use these types of firmware by leveraging globally aware software control from the end of the network.

What is a traditional network?

The most common way of networking, traditional networking uses fixed-function and dedicated hardware and network devices, including switches and routers, to control network traffic.2 These devices have individual functions that work well together and help to support the network.

The ability to scale is a frequent problem for traditional networks. Most switching hardware and software is proprietary and it’s uncommon for APIs to be exposed for provisioning.

Traditional networks tend to synergize well with proprietary provisioning software. Unfortunately for traditional networks, this software is unable to be modified as needed and hardware-centric networking can be very limiting in what it’s able to use.

Traditional networking’s functions and functionality are implemented in the following ways:

  1. The functions are implemented from dedicated devices that use switches, routers and application delivery controls.
  2. The functionality is primarily implemented in application-specific integrated circuits (ASIC) and other dedicated hardware.

How are SDN and traditional networking different?

The biggest difference between SDN and traditional networking is simply that SDN is software-based and traditional networking is usually hardware-based. Being software-based helps SDN with scalability and flexibility, and helps it provide its users with more control and easier resource management, allowing users to virtually manage resources with the control plane.

Unlike SDN, traditional networks use routers, switches and other hardware and physical infrastructure to generate connections and run the networks.

SDN controllers use a northbound interface that communicates with APIs, allowing application developers to program the network. The opposite of this interaction is application developers using traditional networking protocols to program the network.

When compared with traditional networking, SDN can better communicate with hardware that’s using the network. Instead of using physical infrastructure, SDN allows users to apply software for provisioning new devices and allows IT administrators to direct network paths and direct network services.

The biggest difference between SDN and traditional networking is showcased because of virtualization.  SDN generates an abstract copy of your network when it virtualizes your network. This virtualization allows you to provision your resources from a centralized location.

For a traditional network, the physical location of the control plane hinders an IT administrator’s ability to direct the flow of traffic.

For SDN, virtualization transforms the control plane from being physical hardware to being software-based. Virtualization allows the control plane to be accessed through a connected device and gives IT administrators more control with directing the flow of traffic using a centralized user interface (UI). This centralized UI allows users more control over how their networks are configured and how they function. Users can quickly process different network configurations from the centralized UI, an ability that is particularly beneficial for network segmentation.

Because SDN allows IT administrators to provision resources and bandwidths, allowing admins to scale them as needed without requiring an investment of more physical infrastructure, SDN has become a popular alternative to traditional networking. Traditional networking needs new hardware to increase its network capacity. The concept of SDN versus traditional could be summed up by the following phrase: one needs more equipment for expansion and the other needs more keystrokes.


  1. SDN vs Traditional Networking: Which Leads the Way? Fiber Optic Cable Solutions, 22 December 2018.
  2. Difference between Software Defined Network and Traditional Network. Geeks for Geeks, 21 August 2020.