Abstract: In a network system having a plurality of LANs each connecting a plurality of terminals interconnected, a LAN interconnection switching unit for switching and relaying data receives data frames from LANs and sends out a call set-up frame including a call number assigned to a combination of source and destination terminal addresses and addresses of relaying interconnection switching units. The data received from LAN is segmented into packets, which are sent out together with the call number. The interconnection switching unit switches and relays data by using data frame error detection scheme in the LAN. Information for controlling a switching sequence is added to the data frame from the LAN to prevent the interruption by the packet having a different call number.

Abstract: In a network having a plurality of node apparatus connected to a transmission line, each node apparatus segmenting a transmission message into information blocks of a predetermined length and transmitting them to the transmission line in the form of a fixed length packet (cell) having a source address, each node apparatus sequentially stores packets having different source addresses in vacant memory blocks of a buffer memory. There is written in each memory block the packet data as well as a next address pointer indicating a memory block in which the next received packet having the same source address is stored. When a packet containing the last information block of a message is received, stored in a read address queue is the address indicating the memory block which stores the first information block of the same packet.

Abstract: A high-speed ring LAN capable of accommodating at least one public network having a signal transmission rate of 155.57 MHz, and at least one sub-LAN having a signal transmission rate of 100 MHz. The high-speed LAN has a signal transmission rate of 155.52 Mbps.times.n (n is an even number). SONET (Synchronous Optical NETwork) subframes each comprising a 9 bytes.times.9 section overhead area and a 261 bytes.times.9 virtual container 4 (VC-4) area flow in a time-divisional n-multiplexed format. The respective node devices inserted in the transmission path have one or more ports to accommodate sub-LANs or public networks. Information is exchanged in units of a fixed-length packet between a received SONET subframe and an asynchronous packet whereas information is exchanged in units of a byte between the SONET subframe and a synchronous port.

Abstract: In a netowrk system having a plurality of LANs each connecting a plurality of terminals interconnected, a LAN interconnection switching unit for switching and relaying data receives data frames from LANs and sends out a call set-up frame including a call number assigned to a combination of source and destination terminal addresses and addresses of relaying interconnection switching units. The data received from LAN is segmented into packets, which are sent out together with the call number. The interconnection switching unit switches and relays data by using data frame error detection scheme in the LAN. Information for controlling a switching sequence is added to the data frame from the LAN to prevent the interruption by the packet having a different call number.

Abstract: A method of multi-address communication in a loop network formed by connecting a plurality of nodes each provided with a data processor to one another through a transmission line in which, in order for a transmitting node having transmitted a multicast information frame to be able to confirm the delivery of the multicast information frame, the transmitting node transmits a multicast response frame for the delivery of confirmation of the multicast information frame, immediately after the transmission of the multicast information frame, and receiving nodes present information for indicating the reception of the multicast information frame at the address part of the multicast response frame, in the order of node arrangement in the loop network in the direction from the transmitting node toward the downstream thereof, to check the information by each of the receiving nodes and the transmitting node.

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.