A communication system comprises: a plurality of switches divided into a plurality of domains; a plurality of first control apparatuses that control a switch included in a corresponding domain; and a second control apparatus that controls the plurality of first control apparatuses. One first control apparatus corresponding to one domain out of the plurality of domains determines processing content on a packet of first communication between terminals accommodated by different switches included in the one domain based on a first database held by the one first control apparatus. The second control apparatus determines processing content on a packet of second communication between terminals accommodated by switches included in different domains out of the plurality of domains based on a second database held by the second control apparatus.