Patent ID: 8897134

Claim:
A method performed by a network element, for notifying a controller of a change to a packet forwarding configuration of the network element, where the network element is separated from the controller by a communication channel, the method comprising: receiving packet forwarding configuration modification messages from the controller over the communication channel that are operable to control the network element to modify the packet forwarding configuration; determining the change to the packet forwarding configuration of the network element, wherein the packet forwarding configuration specifies how packets are to be forwarded by the network element and specifies to which ports of the network element the packets are to be forwarded; and actively notifying the controller of the change to the packet forwarding configuration by sending a message to the controller over the communication channel, the message in addition to indicating the change also indicating at least one detail about a portion of the packet forwarding configuration after the change, wherein the at least one detail comprises a detail of a flow entry in the flow table after the change, wherein each flow entry includes header fields, counters, and zero or more data forwarding actions to apply to a packet that matches the header fields, and wherein the message containing the detail of the flow entry after the change is sent to the controller without explicit instruction from the controller.