Patent ID: 8687647
Filing Date: 2014-04-01
Classification: H04L

Abstract:
1. A communication node in a communication system in which a plurality of communication nodes are connected by Ethernet in a ring shape, the communication node comprising: a data-frame communication processor that transmits and receives a data frame; a communication-right acquisition processor that, when receiving a token frame and acquiring a communication right, transmits a token-receipt completion notification frame addressed to a source communication node of the token frame, causes the data-frame communication processor to start transmitting a data frame, and releases the token frame when the data frame transmission by the data-frame communication processor is finished; and a logical-ring-status control unit that switches between a transmission mode of disconnecting a logical connection within the own communication node and performing a termination process upon acquisition of the communication right, and a repeat mode of finishing the disconnection of the logical connection within the own communication node upon reception of the token-receipt completion notification frame addressed to the own communication node, wherein the data-frame communication processor discards all received frames when the communication node is in the transmission mode, and forwards a received frame when the communication node is in the repeat mode, and wherein the communication-right acquisition processor, upon reception of a token frame without receiving a token-receipt completion notification frame addressed to the own communication node in the transmission mode, transmits a token-receipt completion notification frame addressed to a source communication node of the token frame and transmits again a data frame which has been transmitted before receiving the token frame transmitted by the other communication node or transmits a newly updated data frame, and thereafter releases the token frame, reception of the token frame without reception of the token-receipt completion notification frame addressed to the own communication node indicating that the token-receipt completion notification frame addressed to the own communication node is lost.