One of the key fundamentals of SDN is disaggregation. Disaggregation of software and hardware in a network and also disaggregation of control and forwarding planes.
The SDN controller is the main brain and controller of an SDN environment. It's a strategic control point within the network and it is responsible for communicating information to:
- Routers and switches and other network devices behind them. SDN controllers uses APIs or protocols (such as OpenFlow or NETCONF) to communicate with these devices. This communication is known as southbound.
- Upstream switches, routers or applications, and the aforementioned business logic (via APIs or protocols). This communication is known as northbound. An example of a northbound communication ...