The instruction set of the forwarding devices is defined by the southbound API, which is part of the southbound interface. Furthermore, the SI also defines the communication protocol between forwarding devices and control plane elements. This protocol formalizes the way the control and data plane elements interact.
- OpenFlow Protocol
- Open vSwitch Database (OVSDB)
- revised open-flow library (ROFL)
- hardware abstraction layer (HAL)
- programmable abstraction of data path (PAD)
In the SDN infrastructure the network intelligence moves from the data plane devices to a logically centralized control system. The physical devices are now simple forwarding elements without embedded control or software to take autonomous decisions. The representative devices in the area of OpenFlow are called OpenFlow Switches.