Method of multi-address communication

A method of multi-address communication in a network formed by connecting, in a ring, a plurality of nodes each coupled with a data processor, through a transmission line having a single transmission direction, wherein an information frame transmitted to said transmission line from one of said nodes is relayed successively by other nodes to return to the originating node, said method comprising the steps of:

• transmitting from a first node of said plurality of nodes a multicast information frame to be delivered to other nodes of said plurality of nodes and subsequently, transmitting a multicast response frame for confirmation of delivery of said multicast information frame to said transmission line, said multicast response frame containing a source address and a destination address;
• relaying from a node, which is in a busy state when said multicast information frame is received by said node, said multicast information frame and said multicast response frame transmitted thereto to a succeeding node unchanged;
• checking a relationship between said source address or said destination address in said multicast response frame and an address stored in a node successful in receiving said multicast information frame, and changing said source address or said destination address in said multicast response frame when a predetermined relationship is ascertained in said checking step, or relaying said multicast response frame to a succeeding node without changing said source address or said destination address;
• and
• determining whether said multicast information frame is to be retransmitted by said first node by checking said source address or said destination address in said multicast response frame returned thereto.