(diagram from OpenFlow: Enabling innovation in Campus Networks)
OpenFlow is a new protocol for controlling how packets are forwarded through switches. Currently switches implement control and forwarding logic within the same device. OpenFlow makes use of existing forwarding hardware but moves the control logic out of the switch to a central controller. The architecture provides fine grain control of traffic, making it possible to engineer the network to implement customized security and performance management strategies.
An interesting video demo shows how OpenFlow can be used to maintain a live connection between two laptops as they move around a wireless network. Similar challenges exist in data centers in maintaining connectivity as virtual machines migrate.
The combination of OpenFlow and sFlow offers exciting possibilities, combining the network wide visibility of sFlow with the centralized control capabilities of OpenFlow creates a dynamic feedback control system that can be used to create intelligent, self optimizing networks.