What Is Software-Defined Networking (SDN)?

Learn more about SDN, including how it works, how to implement it, benefits, and differences between SDN and traditional networking.

What Is Software-Defined Networking (SDN)?

  • SDN is a network management approach that helps improve internal communications and overall network performance. It can use application programming interfaces (APIs) and software-based controllers to communicate with the organization's hardware infrastructure, but also allows network feature virtualization (NFV). Software-defined networking (SDN) helps with the centralized management of networks using software applications. It enables dynamic and programmatically efficient network configurations to improve network performance and monitoring. SDN can also be defined as an efficient and cost-effective architecture that can easily manage high-bandwidth, dynamic applications.

  • The primary function of SDN is to address the architecture of a traditional, complex, decentralized network. Current networks require more flexibility and quick troubleshooting.

    It’s important to know about the control plane and data plane to understand how SDN works.

    • Control plane: The functions and processes determining which path you need to consider to transfer data packets.
    • Data plane: The set of functions and processes that forward packets from one interface to another.

    The role of SDN is to centralize the network by decoupling the data plane and control plane. This helps to program and control the entire network through a centralized system.

    SDN architecture includes three major SDN elements:

    • Applications: Communicate resource requests or information about network
    • Controllers: Receive information from application to route data packets
    • Networking devices: Receive information from controllers about where to move the data
  • Efficient and effective SDN implementation requires the following steps.

    • Define a use case: SDN is a dynamic and broad technology for troubleshooting network performance. Identifying a narrow problem is important before you get started with SDN. Focus on a single use case for tangible, reliable, and measurable results.
    • A cross-functional team: Implementing SDN requires a well-rounded team and a comprehensive approach. You can use SDN monitoring tools to bridge the monitoring gap between the physical and virtual networks and save your time and efficiency for more business-critical tasks.
    • Test in a less critical network area: One of the best ways to initiate SDN implementation is to test it on a less critical network area. The small-scale SDN implementation allows you to safely test your use case without disturbing the entire network.
    • Use an SDN monitoring solution: To ensure your SDN and its physical network are running optimally, you need to adopt SDN monitoring solutions. These solutions help you monitor, visualize, and correlate the performance of your network. You can gain in-depth visibility and insights into SDN technologies to expand and reconcile disparate data into a single pane of glass.
  • Software-defined networking (SDN) helps businesses in a few ways:

    • Increased network control: SDN offers increased control with greater speed and flexibility and improved physical connectivity. It allows you to configure, manage, and optimize network resources via dynamic, automated SDN programs independent of proprietary software. SDN eliminates the need to monitor or program multiple vendor-specific hardware devices manually. Instead, you can control network behavior such as traffic flow by programming a software-based controller to support new services and individual customers.
    • Centralized network infrastructure: As SDN is built on logically centralized topologies, it can help optimize the flow of data passing through the network and intelligently control the management of network resources. It can also be used to prioritize applications that require improved availability. With centralized control of an SDN-based network, you can optimize restoration, bandwidth management, security, and policies. Moreover, it provides a global view of your organization’s network.
    • Robust security: SDN provides in-depth visibility into the entire network, so you can easily monitor potential security threats. It uses smart devices connected to the internet to overcome the challenges of traditional networks and deliver seamless services. It can create separate zones for devices that require different levels of security. Additionally, it quarantines compromised devices to safeguard the rest of the devices in the network.
    • Abstraction of the network: Abstraction enables you to adjust network-wide traffic flow to meet changing needs. Applications that run on SDN technology are abstracted from the hardware used to connect them to the network physically. This helps applications communicate with the network via APIs instead of management interfaces coupled to the hardware.
  • The major difference between traditional networking and SDN-based networking is infrastructure. SDN is a software-based networking approach, while traditional networking is a hardware-based approach. As the control plane is software-based, it becomes easier for SDN to provide flexibility in configuration settings, provision resources, network capacity, and overall network.

    Another difference is security. SDN offers enhanced security, greater visibility, and the ability to define security pathways. As SDN uses a centralized controller, it becomes important to secure the controller to maintain a secure network.

  • The different models of SDN include:

    • SDN by APIs: This model uses an application programming interface instead of an open protocol to control data movement throughout the network.
    • Hybrid SDN: This model combines traditional networking with SDN to support various functions. Traditional networking protocols work on directing traffic while SDN protocols manage traffic and introduce SDN to a legacy system.
    • Open SDN: Open SDN enables you to control the behavior of physical and virtual switches.
    • SDN overlay model: The overlay model creates dynamic tunnels by running a virtual machine over the existing hardware. The virtual network allocates devices to each channel, manages the channel bandwidth, and leaves the physical network untouched.
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