[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) The present invention is based upon and claims the benefit of priority of Japanese Patent Apphcation No. 2012-135031, filed on June 14, 2012, the disclosure of which is incorporated herein in its entirety by reference thereto. The present invention relates to a communication system, a control apparatus, a com-munication method, a control method and program, and relates to a communication system, a control apparatus, a communication method, a control method and program that process packets in accordance with control by the control apparatus. Background [0002] In recent years, technology has been proposed by which a computer performs cen¬tralized control of packet forwarding by communication equipment such as a switch or router. [0003] Patent Literature 1 discloses technology in which switches in a communication system process packets in accordance with an instruction notified by a control apparatus. The control apparatus performs centralized control of a plurality of switches in the communication system. [0004] Non Patent Literature 1 discloses technology in which a plurality of control ap¬paratuses share control of a plurality of switches in a communication system. Citation List Patent Literature [0005] PTL 1: International Publication No. 2008/095010 Non Patent Literature [0006] NPL 1: Rob Sherwood and 6 others: "FlowVisor: A Network Virtuahzation Layer", [Online], [search conducted May 28, 2012], Internet: