• SDN represents a new network architecture that allows for the separation of control and data planes, enabling more intelligent and flexible network management.
  • The technology behind SDN, OpenFlow, facilitates dynamic control of network traffic by allowing real-time communication between the controller and network devices.
  • SDN promotes an open and programmable environment, making it easier to develop and deploy new applications and services, thereby fostering innovation in network infrastructure.

As technology evolves, so do the networks that connect us. Software-defined networking emerges as a revolutionary approach that reshapes traditional networking paradigms. By decoupling the control plane from the data plane, SDN introduces a centralised method for managing network resources.

This leads to greater flexibility, streamlined operations, and enhanced security. Organisations can now respond swiftly to new challenges while ensuring robust performance and reliability. In this blog, we will delve deeper into the fundamental aspects of SD.

Understanding software defined networking

Software-defined networking is a network architecture and management method that separates the network control plane from the data forwarding plane and centrally manages the network control, thereby improving the flexibility, programmability and manageability of the network.

In traditional network architecture, network devices are responsible for data forwarding and control logic, while SDN centralises the network control logic in a central controller, which makes network management more centralised and flexible.

Also read: How does load balancing work in networking?

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The components of SD

SDN provides a programmable, centralised network with SDN controllers, southbound apis, and northbound apis. The SDN controller is the heart of the network, providing a centralised view of the entire network. The southbound API forwards information to switches and routers in the network. Northbound apis are used to enable application communication and service deployment.

A typical representation of the SDN architecture consists of three layers: application layer, control layer, infrastructure layer.These layers communicate using northbound and southbound application programming interfaces.

Application layer: The application layer contains typical network applications or functions used by an organisation, which may include intrusion detection systems, load balancers, or firewalls. Traditional networks will use dedicated devices, such as firewalls or load balancers, while software-defined networks replace devices with applications that use controllers to manage the behavior of the data plane.

Control layer: The control layer represents the centralised SDN controller software that acts as the brain of the software-defined network, which resides on the server and manages policy and traffic across the network.

Infrastructure layer: The infrastructure layer consists of physical switches in the network that forward network traffic to their destinations.

API interface:These three layers communicate using their respective northbound and southbound apis, the application communicates with the controller through its northbound interface, and although other protocols exist, the controller and switch communicate using a southbound interface, such as OpenFlow.

The different models of SD

While the premise of centralised software control of the flow of data in switches and routers applies to all software-defined networks, SDN has a different model.

Open SDN: Network administrators use protocols such as OpenFlow to control the behavior of virtual and physical switches at the data plane level.

API’s SDN: The application programming interface does not use an open protocol, but rather controls how data moves through the network on each device.

SDN overlay Model: Another type of software-defined network runs a virtual network on top of existing hardware infrastructure, creating dynamic tunnels for different local and remote data centers. The virtual network allocates bandwidth through various channels and assigns devices to each channel, while the physical network stays the same.

Hybrid SDN: This model combines software-defined networking with traditional networking protocols in one environment to support different functions on the network. Standard network protocols continue to direct some traffic, while SDN takes care of others, allowing network administrators to phase SDN into legacy environments.