Mitigation of processing load on control device controlling transfer devices within network

A control device that controls a transfer process executed by a plurality of transfer devices, the control device comprising:

• a processor;
• and
• a network connecting device that transmits and receives a message, wherein
• the processor executes a process for notifying each of the plurality of transfer devices of connection information indicating whether each port possessed by each of the plurality of transfer devices is connected to another transfer device among the plurality of transfer devices,
• the network connecting device receives a request message from one of the plurality of transfer devices that has obtained a packet via a port connected to a different device which is different from any one of the plurality of transfer devices,
• the request message requests process information indicating a processing method of the obtained packet,
• the processor decides the process information for the obtained packet,
• the decided process information includes information identifying a transmission source and a destination of a target packet of the processing method, and
• the network connecting device transmits to the plurality of transfer devices a plurality of notification messages each of which includes the decided process information for the obtained packet and information identifying an output port of each of the plurality of transfer devices, the target packet being output from the output port, each of the plurality of transmitted notification messages being received by each of the plurality of transfer devices directly from the control device without an intervention of others of the plurality of transfer devices.

A communication method executed in a network where a control device decides a process of a packet in a plurality of transfer devices, the communication method comprising:

• notifying, by the control device, a first transfer device of a port connected to a second transfer device within the first transfer device;
• receiving, by the first transfer device, a packet from the second transfer device via the port;
• when the first transfer device does not possess information representing the process applicable to the received packet, performing, by the first transfer device, control such that a request message is transmitted after a specified time period elapses from reception of the received packet, the request message being a message for requesting the control device to notify the first transfer device of a process applicable to the received packet, the specified time period being set by the transfer device based on an average delay time of transfer delays that occur in communications with the control device;
• and
• when the first transfer device has obtained process information representing the process applicable to the received packet from the control device before transmitting the request message, processing, by the first transfer device, the received packet in accordance with the obtained process information without transmitting the request message.