An apparatus includes a controller, a converter, and table information storing physical identification information identifying a physical port of first and second physical switches in association with virtual identification information identifying a virtual port of a virtual switch. For each virtual switch, the controller outputs control information determined based on a predetermined protocol and manages the received control information. The converter, based on the table information, converts the physical identification information added to the received control information and identifying a physical port via which the first physical switch has received the control information, into the associated virtual identification information, converts the virtual identification information added to the control information outputted from the controller and identifying a virtual port via which the control information is to be transmitted, into the associated physical identification information, and relays the control information between the controller and the second physical switch.