Abstract: A method of transmitting a large amount of data with priority for use with a CSMA/CD system includes the steps of checking to see if a transmission line has a free space in response to a data transmission request from a node serving as a source node, transmitting, if the transmission line has a free space, a priority transmission notice carried by a data-link-layer protocol signal of the CSMA/CD system from the source node to the other nodes, transmitting data for which the data transmission request has been made from the source node to a node serving as a destination node, and putting the nodes except the source node in a transmission-disabled, reception-enabled state when the priority transmission notice is received by the nodes. Also provided is an apparatus for achieving such a method.

Abstract: A plurality of datagram VCCs, each of which is exclusively for connectionless transfer of data, are established between mutually adjacent exchanges in advance, one of these datagram VCCs is assigned exclusively for connectionless data communication and connectionless communication is performed using this datagram VCC. Specifically, an originating terminal disassembles connectionless data into data cells, inserts a cell (a leading cell), which indicates the destination address of a terminal that is the destination of the data, at the head of the data cells and then sends the leading cell to the exchange prior to the data cells. The exchange assigns a prescribed datagram VCC for connectionless communication upon referring to the destination terminal address indicated by the leading cell and thenceforth uses this VCC to transmit data cells having line identifier identical with that of the leading cell.

Abstract: A local area network (LAN) connection method runs an existing LAN application in an asynchronous transfer mode (ATM) network to connect LANS. The LAN connection method includes the steps of (a) in a LAN emulation (LANE) protocol which operates an existing network in the ATM network, connecting LAN emulation servers (LESs) which mainly cope with addresses from medial access control (MAC) addresses to ATM addresses in emulated LANs (ELANs) by a virtual channel connection (VCC) for transferring a LAN emulation address resolution protocol (LE ARP) which inquires the ATM address from the MAC address, and (b) transferring a LE ARP request with respect to a LAN emulation client (LEC) in a second ELAN to a LES in the second ELAN when a LES in a first ELAN receives the LE ARP request from a LEC in the first ELAN.

Abstract: In a switching hub capable of realizing a high-speed LAN communication, this switching hub is equipped with a switch unit and a plurality of ports connected to this switch unit. When a frame is received from a terminal, each of these ports attaches a tag to which a transmission source LAN number has been set to this received frame, and thereafter supplies the frame with this tag to the switch unit. When the frame with tag is received from another port within another switching hub, the port directly supplies this frame with tag to the switch unit. The switch unit registers the transmission source LAN number of the supplied frame, a transmission source MAC address, and an input port number into a LAN table. While such a port for supplying a frame is determined, either a transmission source address of this frame or a transmission source LAN number thereof is used as a retrieve key so as to try to read out the port number from the LAN table.