Abstract: The invention relates to a method of controlling errors in the transmission of packets transmitted over at least one transmission link between a transmitter and a receiver, the said transmitter receiving from an input multiplex packets belonging to a plurality of end to end associations or groups of end to end associations and transmitting them in the form of sequences of packets over a transmission line, the receiver, on reception of a packet, verifying whether it is correctly received and if so, delivering it to an output multiplex, and if not, sending to the transmitter a negative acknowledgement so that the transmitter can re-transmit it.

Abstract: A transmission buffer or buffers storing therein transmission cells for at least 2 (W-n.sub.a) cell time assuming that a window size in a ring is W cells and a number of transmission cells allocated to a node in said W cells is n.sub.a pieces, a transmission cell number counter for counting a number of transmission cells from the node within the W window size from a current point of time, and a transmission control means for sending out the transmission cells stored in said transmission buffer to a transfer path if a number of cells indicated by said transmission cell number counter is within a number of transmission cells allocated to the node are provided. Also at least 2n.sub.a pieces of transmission buffers are provided as transmission buffers assuming that a number of transmission cells allocated to the node is n.sub.a pieces.

Abstract: This invention provides a frame relay apparatus and a relay method with an efficient transfer time, regardless of the transmitting rates of the input signal and the output signal. A route control table which corresponds the transmitting line number to the transmitting logical link number by using the receiving line number and the received logical link number of the header of the received frame is provided as is a line attribute table which stores the transmitting rates of the input signal and output signal. Furthermore, the line attribute table to store the transmitting rates of the input signal and the output signal and a comparison control mechanism to calculate the necessary buffering amount of the sending buffer based on the frame length of the concerning received frame which is gotten at or before the receiving time of the data of the received frame are provided.

Abstract: An inter-local area network (LAN) connecting system in which LANs are connected to an asynchronous transfer mode (ATM) switching network by respective bridge devices to effect communication between terminals connected to different LANs through the bridge devices and the switching network. Logical connections are set between the bridge devices in advance to transfer cells, which are information units of data transfer.

Abstract: A cell exchange apparatus wherein cell input ports and cell output ports are divided into a plurality of groups and input cells are multiplexed for each group. Multiplexed cells are selected in accordance with their addresses with respect to output port groups and buffered by use of a plurality of buffers. Writing and reading of cells with respect to the buffers are controlled by a memory controller in accordance with the load on each buffer.

Abstract: This invention relates to a time-division transmission method for a plurality of terminals connected to a looped transmission line, in which a plurality of slots being provided with regions, where three kinds: "Free", "Busy" or "Neutral" of access control information are set, are made to circulate on the transmission line, so that when the transmission apparatus at the terminal having data to be transmitted receives a slot of "Free", a necessary number of subsequent slots to the slot of "Free" are continuously used to carry out data transmission, the access control information at the slot in use is changed to "Busy", the access control information of a slot at the head of the slots not used is set to "Free", and an access control information of a slot subsequent to the above slot is set to "Neutral".