OpenFlow is an open standard network protocol used to manage traffic between commercial Ethernet switches, routers and wireless access points. OpenFlow enables software-defined networking (SDN) for programmable networks and is based on an Ethernet switch, with an internal flow-table and a standardized interface to add and remove flow entries.
The basic idea behind OpenFlow is that you can connect multiple switches -- and even networks -- together to create a flow, and then manage the entire infrastructure, setting policies and managing traffic type accordingly. It allows for deployment of innovative routing and switching protocols in your network for many different applications, including virtual machine mobility and high-security networks.
OpenFlow got its start as a research project led by Guido Appenzeller while at Stanford. It is currently being implemented by major vendors, and OpenFlow-enabled switches are commercially available.