Relay device for selecting an optimal path

A relay device connected to a plurality of other relay devices through a plurality of physically different routes to constitute a network, comprising:

• a plurality of physical ports physically connected to the plurality of other relay devices on the network to form a plurality of physical links;
• a setting unit setting one or more logical links in a physical link of the plurality of physical links, each of the one or more logical links having a communication band equal to/lower than that of the physical link, by controlling the communication band in a way that limits a transmission rate of packets transmitted to any one of the other relay devices through the one or more logical links;
• an evaluation unit adding, when a control packet is transferred to any one of the other relay devices through a logical link of the one or more logical links, a value obtained by subtracting an evaluated value of the physical link in which the logical link is set from an evaluated value corresponding to the transmission rate of the logical link to an evaluated value in the transferred control packet;
• and a selecting unit selecting, when there are a plurality of routes from a start-point device among the other relay devices which becomes a transmission start point of the control packet to the relay device, one of the routes based on evaluated values accumulated by the relay devices included in the routes from the start-point device to the relay device.