What Is Software Defined Networking (sdn)?

By Author: Cisnet Training
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Software defined networking (SDN) is a revolutionary new concept that seeks to optimise the functioning of a network and drastically improve the efficiency. In SDN, there is a central control layer that seeks to regulate the flow of information and the associated use of bandwidth and other parameters. Thus, an SDN controller acts as a virtual brain of the network and offers administrators a bird’s eye view of the overall network. They can not only monitor the traffic easily, but also dictate to the underlying systems like switches, routers and other network gear, how the network traffic should be handled. Thus network engineers can respond easily to changing business needs and shape the traffic flow, without hunting for and manipulating individual switches.

The SDN controller is the central brain and acts as an intermediary between two levels. The level above the controller is the application layer and all data travelling to that level is said to be northbound. The level below that layer is said to be the infrastructure layer and all data travelling in that direction is said to be southbound.
An application ...
... programming interface (API) refers to a set of protocols and tools that are used to build software applications. APIs help express software in terms of its various components like inputs, output and operations. Thus, in a SDN, northbound APIs communicate with all the applications on top, while the southbound APIs communicate with eth switches and routers below.

The main advantage of adopting a SDN is the fact that capital and operational expense is reduced significantly. With optimization strategies, functional separation and automation, significant cost savings can also be achieved. Further, higher reliability in network functioning is obtained and programmable interfaces and switches mean that scaling up or scaling down of network operations is easy. This is simply because traffic loads can be adjusted quickly, dynamically and cost-effectively. SDN thus seeks to be a real bridge between the network intelligence part and the physical hardware part, without any compromise on functionality or efficiency. Manual administration and the time and expense associated with reconfiguration are significantly reduced.

At a time when existing loopholes in networking technology like vendor dependence, complexity and inability to scale up or down quickly are leading to a slow growth, SDN looks to be the beacon of hope. With the heralding of a new era that is more data driven, cloud-centric and application intensive at every touch point, SDN looks to be the sure answer to future progress.