Abstract: In a network system wherein a plurality of terminal devices communicates with each other via respective node devices over a ring transmission line, a transmitting node device can confirm whether a multicast information transmission has succeeded or failed. The transmitting node device send a response frame after a multicast information frame. A receiving node device relays the multicast information frame and a response frame from the upstream node device to the downstream one when the multicast information has been received successfully, or in case of a failure in receiving the multicast information, sends a response frame to the downstream node device by changing at least part of the response frame from the upstream node device. The transmitting node device can determine from a received response frame if there is one or more of the receiving node devices which cannot receive the multicast information.

Abstract: Multi-network system for transmitting data among a plurality of stations, each of which is connected to one of transmission lines, a plurality of said transmission lines being connected with each other through bridge stations, in which the numbers of the transmission lines, with which in final destination station and the source station are connected respectively, are set as the destination address and the source address in the data frame to be sent; in the case where the bridge station receives a frame of data to be relayed between different transmission lines, the bridge station identifies the relay by the destination address, stores the data frame in a memory means storing data, which should be sent by the bridge station itself; attaches to the data to be relayed a flag, in which the relay indication is set, and to the data not to be relayed a flag, in which the relay indication is not set; and when the data are sent by said station, in the case where the flag attached to the data represents the relay, the

Abstract: Multi-network system for transmitting data among a plurality of stations, each of which is connected to one of transmission lines, a plurality of said transmission lines being connected with each other through bridge stations, in which the numbers of the transmission lines, with which in final destination station and the source station are connected respectively, are set as the destination address and the source address in the data frame to be sent; in the case where the bridge station receives a frame of data to be relayed between different transmission lines, the bridge station identifies the relay by the destination address, stores the data frame in a memory means storing data, which should be sent by the bridge station itself; attaches to the data to be relayed a flag, in which the relay indication is set, and to the data not to be relayed a flag, in which the relay indication is not set; and when the data are sent by said station, in the case where the flag attached to the data represents the relay, the