US Patent 9313088 Network system and network managing method

A controller completes the setting of a flow entry to a switch previously before the communication of a virtual machine starts. Specifically, the controller sets information of the virtual machine and information of a server on which the virtual machine operates. The controller detects the information of the server under the switch through the switch. When the set server information and the detected server information match to each other, the controller sets a flow entry for a packet destined to the virtual machine to the switch based on information of the virtual machine on the server. After that, the virtual machine starts communication.