An object of the present invention is to reflect a band of the
bottleneck into the cost, to select an optimal path, and to enhance an efficiency of the net utilization without making a setting or a modification to the apparatus (bridge etc.) in which the path control protocol operates in a case where a difference exists between an actually utilizable rate (a band of the
bottleneck) in the path between the bridges etc. and a
link rate of the connection link such as the bridge etc. in a net in which the apparatus (bridge etc.), in which the path control protocol (STP etc.) for automatically computing a cost of a link by a physical band of the connection link operates, exists. In the
system of the present invention, the port manager within the
relay apparatus, upon
receipt of a notification of the
link rate from the port, investigates which side, out of the WAN side and the LAN side, becomes a
bottleneck, and the cost rewriter within the
relay apparatus rewrites the root
path cost field within the BPDU in conformity to the rate of the bottleneck.