Networking as we know it is on the verge of a momentous change, thanks to a path-breaking technological concept known as software defined networking (SDN).

 

SDN represents a paradigm shift to the way networking elements operate. It is based on the OpenFlow Protocol and is the result of pioneering work by Stanford University and University of California, Berkeley.

 

Today’s networks and network elements have been largely closed and based on proprietary architectures and operating systems. Switching and routing of data packets happen in the same network elements, such as the router. SDN decouples the routing and switching of the data flows and moves the control of the flow to a separate network element namely, the flow controller. The motivation for this is that the flow of data packets through the network can be controlled in a programmatic manner.

 

A Flow Controller can be typically implemented in a standard PC. In some ways this is reminiscent of Intelligent Networks and Intelligent Network Protocol which delinked the service logic from the switching and moved it to a network element known as the service control point.

 

The OpenFlow Protocol has three components. The flow controller, the OpenFlow switch and the flow table, and a secure connection between the controller and switch. The protocol is an open source API specification for modifying the flow table that exists in all routers, Ethernet switches and hubs. The ability to securely control the flow of traffic programmatically opens up amazing possibilities.

 

Alternatively, existing branded routers can implement the OpenFlow Protocol as an added feature. The move will enable these routers and Ethernet switches to support production traffic and research based traffic using the same set of network resources.

 

The single greatest advantage of separating the control and data plane of network routers and Ethernet switches is the ability to modify and control different traffic flows through a set of network resources. In addition, SDNs also include the ability to virtualize the network resources. Virtualized network resources are known as a “network slice”, which can span several network elements including the backbone, routers and hosts.