What is Software Defined Networking (SDN)?

SDN is the abbreviation of software defined networking, which is a network architecture that separates the control plane from the data plane. It involves decoupling network intelligence and policies from the underlying network infrastructure and providing a centralized management and control framework.

How does Software Defined Networking (SDN) work?

SDN works by using a centralized controller that manages and configures network devices, such as switches and routers, through open protocols such as OpenFlow. The controller acts as the brain of the network, allowing administrators to centrally define network behaviors and policies, which are then enforced throughout the network infrastructure. SDN networks can be divided into three layers, each consisting of different components.

Application Layer: The application layer contains the network applications or functions used by the organization. There may be multiple applications related to network monitoring, network troubleshooting, network policy, and security.

Control layer: The control layer is the middle layer connecting the infrastructure layer and the application layer. It refers to the centralized SDN controller software, which serves as the land of the control plane and the intelligent logic connected to the application plane.

Infrastructure layer: The infrastructure layer consists of various network devices, such as network switches, servers, or gateways, which form the underlying network and forward network traffic to its destination.

In order to communicate between the three layers of the SDN network, northbound and southbound application programming interfaces (APIs) are used. The northbound API enables communication between the application layer and the controller, and the southbound API enables communication between the controller and network devices.

What are the different models of SDN?

Depending on how the controller layer connects to the SDN devices, SDN networks can be divided into four different types, which we can categorize as follows:

Open SDN

OpenSDN has a centralized control plane and uses OpenFlow as the southbound API for traffic from physical or virtual switches to the SDN controller.

API SDN

APISDN, unlike open SDN, does not rely on open protocols, but instead controls how data moves through the network on each device.

Overlay SDN

Overlay SDN does not solve the underlying physical network, but builds a virtual network on top of the current hardware. It runs on the overlay network and provides a tunnel with a channel to the data center to solve the connection problem of the data center.

Hybrid SDN

Hybrid SDN, also known as automation-based SDN, combines SDN features with traditional network equipment. It uses agents, automation tools such as Python, and components that support different types of operating systems.

What are the advantages of SDN?

Different SDN models have their own advantages. Here, we will only discuss the general benefits of SDN for networking.

Centralized management

Centralization is one of the main advantages of SDN. Data center managers can benefit from SDN networks that enable centralized management of the network using central management tools. It breaks down the barriers created by traditional systems and provides greater flexibility for virtual and physical network configurations, all from one central location.

Safety

Although the trend towards virtualization has made it more difficult to protect the network from external threats, SDN brings huge advantages. SDN controllers provide network engineers with a centralized location to control the entire security of the network. Through the SDN controller, it is ensured that security policies and information are implemented within the network. And SDN is equipped with a single management system, which helps to enhance security.

Cost savings

SDN networks offer users low operating costs and low capital expenditure costs. On the one hand, the traditional way to ensure network availability is through redundancy of additional equipment, which of course increases costs. Compared with the traditional way, software-defined networks are more efficient without the need to purchase more network switches. On the other hand, SDN works well with virtualization, which also helps reduce the cost of adding hardware.

Scalability

Since OpenFlow agents and SDN controllers allow access to various network components through their centralized management, SDN provides users with more scalability. Compared with traditional network settings, engineers have more options to change the network infrastructure immediately without having to manually purchase and configure resources.

In summary, SDN plays a vital role in modern data centers where agility and efficiency are critical. By virtualizing network resources, SDN enables administrators to automate network management tasks and simplify operations, thereby improving efficiency, reducing costs, and accelerating time to market for new services.

SDN is changing the way data centers operate, providing tremendous flexibility, scalability, and control over network resources. By adopting SDN, organizations can unlock the full potential of their data centers and stay ahead in an increasingly digital and connected world.