A communication system includes: a control apparatus configured to set control information, which causes each control target switch to distinguish a link layer discovery protocol packet of a first network from a link layer discovery protocol packet of a second network different from the first network and to perform corresponding predetermined processing, in each control target switch; a group of switches each of which is configured to transmit a link layer discovery protocol packet of the first network to a predetermined topology management apparatus in accordance with control information set by the control apparatus; and a topology management apparatus configured to manage a network topology configured by the group of switches on the basis of information included in a link layer discovery protocol packet of the first network received from each of the switches.