Communication system for a ring-type network

In a communication network system having a plurality of nodes connected to each other by a single ring-type network including a transmission line, a communication method comprising the steps of:

• equipping the nodes on the transmission line with a frame insertion buffer;
• circulating a plurality of tokens corresponding to the nodes, respectively, on the transmission line wherein the number of tokens is approximately the same as the number of nodes;
• acquiring, when any one of the nodes has detected a circulating token corresponding to itself, the token corresponding to itself if the node holds data to be transmitted,
• transmitting, after a node acquires the token corresponding to itself, at least part of the data to a destination node on the transmission line only when the frame insertion buffer is empty;
• storing data and tokens arriving at a node on the transmission line while the node is transmitting data in the frame insertion buffer;
• and
• eliminating data from the transmission line by the destination node.

A communication method which is used by nodes on a ring-type transmission line comprising the steps of:

• equipping the nodes on the transmission line with a frame insertion buffer;
• circulating a plurality of tokens corresponding to the nodes, respectively, on the transmission line, wherein the number of tokens is approximately the same as the number of nodes;
• wherein each node has an own node number respectively,
• the token has a node number field respectively,
• one of the node numbers is written into the node number field of the each token in a manner that a different node number is initially written into a node number field of a different token,
• said communication method further comprising a transmitting method and a receiving method,
• the transmitting method comprising the steps of:
• a token receiving step where a node receives a token circulating on the transmission line,
• a token judgment step where the node which received the token in said token receiving step judges that if a node number written in a node number field of the token which is received, coincides with an own node number of the node which received the token, the received token can be usable,
• a frame generation step where when the token which is received by the node is usable according to the token judgment step, and when the node which received the token holds data to be transmitted, the node generates a frame including at least a portion of the held data and a node number of a destination node of the data on a basis of the data and the received token,
• a frame transmission step where the node which generated the frame transmits the frame to the transmission line,
• a store step where in the case that when the node is transmitting the frame or the token to the transmission line in the frame transmission step, another frame which is different from said frame which is being transmitted and/or another token which is different from said token which is being transmitted arrive at said node which is transmitting the frame or the token, the another frame and/or the another token are stored in the frame insertion buffer of the node which is transmitting the frame or the token, and
• the receiving method comprising the steps of:
• a frame receiving step where a node receives a frame from the transmission line,
• a frame judgment step where such judgment is executed by the node which received the frame, that a node number included in the received frame coincides with an own node number of the node which received the frame,
• a frame elimination step where only when the node number is coincided with the own node number in the frame judgment step, the node which received the frame in the frame receiving step does not transmit the received frame to the transmission line, and does transmit only the token which had been added to complete the received frame, to the transmission line.