CUSP-based Port Information Reporting
CUSP allows a forwarder to report its port information to a controller through a control channel.
In Figure 1, after a control channel is established, the controller proactively queries port information from the forwarder. To achieve this, the controller sends a Multipart Request packet to query the port information of the forwarder. Upon receipt of the packet, the forwarder returns Multipart Reply packets to bulk report port information. If there are port changes, such as port status changes, the forwarder proactively sends Port Status packets to notify the controller of the changes.
