What is Software-Defined Networking?

To better understand how SDN works, it helps to define the basic components that create the network ecosystem. The components used to build a software-defined network may or may not be located in the same physical area. These include:

·         Applications – Tasked with relaying information about the network or requests for specific resource availability or allocation.

·         SDN controllers – Handle communication with the apps to determine the destination of data packets. The controllers are the load balancers within SDN.

·         Networking devices – Receive instructions from the controllers regarding how to route the packets. 

·         Open-source technologies – Programmable networking protocols, such as OpenFlow, direct traffic among network devices in an SDN network. The Open Networking Foundation (ONF) helped to standardize the OpenFlow protocol and other open source SDN technologies. 

By combining these components, organizations get a simpler, centralized way to manage networks. SDN strips away the routing and packet forwarding functions, known as the control plane, from the data plane, or underlying infrastructure. SDN then implements controllers, considered the brain of the SDN network, and layers them above the network hardware in the cloud or on-premises. This lets teams use policy-based management—a kind of automation—to manage network control directly. 

SDN controllers tell switches where to send packets. In some cases, virtual switches that have been embedded in software or the hardware will replace the physical switches. This consolidates their functions into a single, intelligent switch that can check data packets and their virtual machine destinations to ensure there are no issues before moving packets along.