<p>A communication system provided with a plurality of communication devices, wherein packets are transferred through a communication path among the plurality of communication devices. When a first communication device among the plurality of communication devices verifies connectivity of the communication path by making any one of the communication devices on the communication path perform loopback of a packet, the first communication device stores first information to designate the communication device which is to perform the loopback of the packet into a first area of the header information of the packet, stores second information relating to a loopback point of the packet in the designated communication device into a second area of the header information of the packet, and transmits the packet provided with the first information and the second information.</p>
