OpenFlow Controller

Multiple controller connections can be used for redundancy purposes, such as when using a single controller with multiple addresses. Multiple controller connections can also be used to support active-standby controllers.

Regardless of the intended use of multiple controller connections, the device allows all the controller connections to concurrently manage the flow table. That is, flow entries in the flow table are not identified as belonging to any specific controller connection. In an active-standby controller deployment, controllers themselves must coordinate their actions and active-standby states. The device responds to all connected controllers without distinction.

The device supports two types of controller connections (also called modes): active and passive. An active connection is one for which the device initiates (seeks) the TCP connection to a given OpenFlow Controller address. With a passive connection, the device passively waits for the controller to initiate (seek) the TCP connection to the device. Active mode is commonly used with production controllers, while passive mode is commonly used for testing purposes in experimental environments. Optionally, a controller connection can also use SSL encryption.