Patent ID: 8724518

Claim:
A communication system consisting of at least two ring networks, each ring network including a plurality of nodes, said communication system comprising: a plurality of combinations of nodes, each combination of nodes is formed by selecting at least one node from each of the ring networks without overlapping with other nodes on the same ring network to which a selected node belongs, wherein the nodes forming the combination of nodes are connected with each other in the same combination of nodes; and a plurality of terminals, wherein each terminal transmits and receives a data frame and is connected to any of said nodes forming to the same combination of nodes, wherein said node belonging to said combination of nodes determines a destination ring network to distribute the data frame received from the terminal according to predetermined conditions, and when having determined own ring network, which is a ring network to which said node belongs, as the destination ring network to distribute the data frame, obtains a destination terminal accommodating node which accommodates a destination terminal of the data frame based on an address of the data frame and information related to topology of the ring networks, and transmits the data frame to the destination terminal accommodating node, and when having determined other ring network, which is a ring network to which the other node in the same combination of nodes belongs, as the destination ring network to distribute the data frame, transmits the data frame to the other node to transmit the data frame through the other ring network, said predetermined conditions include a frame distribution algorithm and transfer conditions including an address of the data frame, a network load and priority, and said information related to topology includes a topology state, failure occurrence condition and network connection information in the ring network corresponding to each of the nodes forming the combination of nodes.