What Is Software-Defined Networking (SDN)?

Software-defined networking (SDN) simplifies the deployment, management, maintenance and troubleshooting of networking infrastructure by abstracting the network control logic from physical devices such as routers and switches. 

While already well established, it is becoming an increasingly integral aspect of modern data center systems and operations. Some reports, for example, have estimated that the value of the global data center SDN market may range anywhere from $30 billion to more than $60 billion by mid-decade.

Regardless of the eventual figures involved, this represents significant growth and highlights the increased adoption of software-defined networking architecture by enterprises and data center network buyers.

What is software-defined networking (SDN)?

In short, software-defined networking (SDN) describes a technology that separates the control plane of network devices from the data plane that relays network traffic.

It features software-defined controllers that create logical overlays abstracted from the underlying network hardware to deliver intent-or policy-based management of the overall network. SDN optimizes the data center network and facilitates faster, automated provisioning of resources, integration with cloud orchestration platforms, pervasive application-oriented visibility, and programmatic network management.

SDN architecture consists of three major components:

1. Networking devices: These devices receive information from controllers on how to forward and route packets.
2. SDN controllers: The controllers are the core element of SDN technology. These devices control the flow and policy that determine the most optimal and secure route to the destination. They enable automation and policy enforcement through a centralized management interface. Software-defined networking controls network packet flows across physical and virtual network environments.
3. Day two operations applications: These applications monitor the traffic flows and policies. They simplify troubleshooting and capture forensic information regarding previous traffic flows. This data is valuable in modeling policy change before implementing any policies that may negatively impact the business. Day two operations applications allow you to visualize the network in a GUI interface and ensure traffic is only flowing as it is intended to flow. By incorporating application monitoring tools with the day two operations platform, the source of any underperforming application is quickly and easily identified. Remediation steps are recommended or can be pushed into the configuration.

Intelligent switching and routing decisions

While separating the control and data planes is the core concept behind software-defined networking technology, that's not all there is to it. A properly configured SDN environment also has centralized intelligence for a full view of the network.

SDN allows for simplifying configurations via automation and change policies across the enterprise, between multiple data centers and into public cloud. Network administrators can view all devices and TCP flows within a typical software-defined networking environment, enabling them to slice up the network to support a variety of configurations and applications.

Types of software-defined networking (SDN)

In general, there are four significant types of SDN:

1. Vendor-specific overlay model software-defined networking: This SDN type creates a virtual network over existing hardware to provide tunnels that contain channels to data centers. The model assigns devices to channels and allocates bandwidth in each channel.
2. Open software-defined networking: This type of SDN uses open protocols to control the physical and virtual devices that route data packets.
3. API software-defined networking: This uses programming interfaces, also referred to as southbound APIs, to control data flow to and from networking devices.
4. Hybrid model SDN: Often used as a phase-in approach to SDN, hybrid model SDN combines traditional and software-defined networking to enable optimal protocols assignment to each type of traffic.

The benefits of software-defined networking (SDN)

Essentially, SDN architecture centralizes network control and management to enable scalability and flexible resource allocation.

Organizations typically use software-defined networking technology to quickly reconfigure and manage network resource usage via policy-based management and automated provisioning. The latter enables optimal efficiency of network resources and empowers organizations to stay agile when responding to fluctuations in resource demand. 

Other benefits of SDN include:

• Network programmability: SDN enables the programmability of network behavior through software applications using open APIs. With this, administrators can tailor network behavior as they see fit to support new services and unique customer requirements.
• Ease of configuration: Software-defined networking uses vendor-specific controllers or open controllers. The controllers provide ease of setup, optimization, and securing and troubleshooting of network resources.
• Greater security: From a centralized controller, consistent policies can be set to control access to applications across the network by workload type or network segments.
• Reduced network complexity: Network administrators will no longer have to configure, manage and troubleshoot on a switch-by-switch basis. Software-defined networking will also increase visibility into the traffic as it passes through the network infrastructure. Administrators will benefit from reduced complexity across all network architectures — whether private, public, hybrid or multicloud.

Understanding software-defined networking (SDN)

Enterprises embarking on digital transformation initiatives typically adopt technologies, infrastructures and architectures that will enable agility, flexibility and innovation. 

Achieving these in a data center networking context requires the adoption of network automation technologies such as software-defined networking.

Want to gain an even greater understanding of software-defined networking? Learn more about how World Wide Technology can help your company get the most out of SDN.