A control apparatus determines one of a plurality of relay devices as a representative relay device to manage a relay destination of content data in a session to be established. In response to receiving a request for starting relay of content data, from a communication terminal, the control apparatus transmits, with a request for starting relay of content data, relay device identification information for identifying the representative relay device to a relay device connected to the communication terminal, to cause the relay device to further transmit the request for starting relay of content data to the representative relay device identified with the relay device identification information of the representative relay device.