Patent ID: 7751413

Claim:
A communication system, comprising: at least a first communication node, having a first function to realize transfer of a packet, and a second function, being an additional function different from said first function, and a second communication node having said first function, and said first communication node grasps address of said second communication node, wherein: said first communication node transmits a search packet to said second communication node for the purpose of searching a communication node having said first function and said second function; and said second communication node transmits a response packet including predetermined information in response to the receiving of said search packet; and a third communication node, having said first function and said second function and being a first receiver of said response packet, grasps that it is a search object of said first communication node upon receipt of said response packet, wherein: said search packet is transferred without modifying the packet from said first communication node to said second communication node, and after said second communication has received said search packet transmitted from said first communication node as it is, it is arranged that said response packet is transmitted, which has source address of said search packet as destination address.