Star topology local area network.

摘要

A star topology local area network comprises a data bus (4), a receive-not-ready bus (5), a plurality of bus access units (2) associated respectively with user terminals (1) for receiving a request therefrom, and an arbiter for assigning priority to one of the bus access units when requests for transmission occur simultaneously. Each of the bus access units comprises a transmit buffer (9) for storing a packet from the associated user terminal and forwarding it to the data bus when priority is assigned to it and a receive buffer (8) for storing a packet from the data bus and forwarding it to the associated user terminal. An address filter (7) is provided in each bus access unit to detect a packet addressed to it and applies a receive-not-ready signal to the receive-not-ready bus when the receive buffer has an insufficient capacity to receive the detected packet. A bus access controller (10) is connected to the receive-not-ready bus for terminating the transmission of a packet in response to the receive-not-ready signal. The storage capacity of the transmit buffer is also monitored and a proceed-to-send signal is transmitted from the bus access unit to the associated user terminal indicating the permission of transmission when the detected storage capacity is sufficient to receive a packet from the terminal.