A communication system including first, second, and third nodes interconnected via interconnect links, a primary path composed of an interconnect link between the first node and the third node, and a secondary path composed of an interconnect link between the first and second nodes and an interconnect link between the second and third nodes, wherein when the first node and the third node function as a transmitting node and a receiving node respectively, having a path multiplexing function to communicate with each other using bandwidths of a plurality of paths simultaneously, the first node transmits, to the second node, a path multiplexing request message for requesting communication with the third node, and when receiving the path multiplexing request message, the second node functions as a relay node and determines whether the primary path and the secondary path can be logically multiplexed by providing, to the first node, the bandwidth of the interconnect link between the second and third nodes, and if path multiplexing is possible, the second node returns a path multiplexing acknowledgement message to the first node, and the first node, in response to the path multiplexing acknowledgement message, multiplexes the primary and secondary paths to communicate with the third node.