SDN (Software Defined Networking)
Software Defined Networking (SDN) is an architectural approach to building and managing networks in which traffic control is moved from hardware to the software layer. This principle makes it possible to flexibly change network configurations, quickly respond to load fluctuations, and automate the management of large numbers of network devices.
In traditional networks, control and data forwarding functions reside within the same device, which complicates updates, scaling, and maintenance. In the SDN model, the control plane is moved to a dedicated software controller, while network devices act as simple traffic forwarders.
Core components
The SDN architecture is built on three key layers:
- Application layer. This layer contains programs that define network logic, resource-allocation policies, and routing rules.
- Control layer, where the SDN controller operates. The controller is responsible for decision-making, telemetry collection, network state analysis, and sending instructions to the lower layer.
- Data plane, which includes switches and routers that execute controller commands and ensure the actual movement of packets.
Operation mechanism and protocols
SDN uses standardized protocols for interaction between the controller and network devices. The most common is OpenFlow, which allows the controller to generate action tables for hardware devices.
With such protocols, administrators can centrally manage network rules, modify routes, organize segmentation, filtering, load balancing, and traffic prioritization. Network management becomes more transparent and predictable because network logic is defined by preconfigured scenarios.
Use cases and benefits
SDN is widely used in data centers, cloud infrastructures, corporate networks, and environments with highly dynamic workloads.
For example, in a data center, SDN can automatically redistribute traffic between servers, increase the bandwidth of specific segments when needed, or restrict access according to security policies.
In provider networks, SDN is used to optimize backbone traffic, support network function virtualization, and accelerate the deployment of new services.
Examples
A common use case is dynamic routing of virtual machine traffic in a cloud platform. When the load increases on one node, the controller automatically updates routing rules and redirects packets to less loaded resources.
Another example is network segmentation in a corporate environment. The controller creates separate logical segments for departments and manages access policies, reducing the risk of security incidents spreading.
FAQ
SDN is a method of managing a network through a software controller rather than configuring each device manually.
In traditional networks, control is built into hardware, while in SDN it is centralized in a software controller, making the network more flexible.
In data centers, cloud environments, corporate networks, and service provider infrastructures.
Yes. Switches and routers typically need to support protocols such as OpenFlow.
Yes. Centralized policy management and network segmentation enhance security.
