In a network device to be used for a packet handling, the network device includes a first unit to communicate with a controller according to a first protocol, and to receive a packet handling rule from the controller which is capable of sending the packet handling rule to a plurality of the network devices via a network between the controller and the network device. A second unit classifies, based on a classification rule for classifying a received packet, whether to handle the packet according to the packet handling rule sent from the controller or to handle the packet according to a table entry that the network device autonomously set based on a second protocol. A third unit requests the packet handling rule to the controller when the packet handling rule for forwarding the received packet is not set in the network device.