A method of exchanging information by the Internet protocol in the form of datagrams each including a TOS field normally dedicated to receiving routing parameters. The method includes configuring network equipment to define an identification zone in the TOS field and associating equipment of a first type with identifiers that can be encoded in said identification zone. When a piece of equipment of the first type sends a datagram to a piece of equipment of the second type, the identifier of the piece of equipment of the first type in question is encoded in the identification zone. When the datagram is received by the equipment of the second type, it is first checked that the identifier appears in a table of authorized identifiers prior to accepting the datagram.