OpenFlow

A Protocol used in Software-defined Networking (SDN) for communication between the controller and the Packet Switches.

Messages

From controller to switches

The controller can send the following messages:

• Configuration: Allows the controller to query and set a switch’s configuration parameters.
• Modify-State: Used to add/delete or modify entries in the switch’s flow table and set switch port properties.
• Read-State: Used to collect statistics and counter values from the switch’s flow table and ports.
• Send-Packet: Send a specific packet from a specific port from a switch. This message has the packet as a payload.

From switch to controller

The controlled switch can send the following messages:

• Flow-Removed: Informs controller that a flow table entry has been removed, e.g. by a timeout, or received Modify-State message.
• Post-Status: Inform controller of change in port status.
• Packet-In: Sends packets not matching any flow table entry to the controller for further processing.