Abstract: In an interface module for connecting user terminals of the carrier sense multiple access collision detection (CSMA/CD) local area network (LAN) to a different access mode switching network, a transmit buffer is connected at one end through a transmit data channel to a user terminal and connected at the other end to a desired swtching system. A receive buffer is connected at one end to the switching system to store a receive packet supplied from it. An OR gate is provided having a first input connected to the transmit data channel, a second input connected to the other end of the receive buffer and an output connected through a receive data channel to the user terminal. A detector circuit detects when a transmit packet is received from the user terminal.

Abstract: A star topology local area network comprises a data bus, a receive-not-ready bus, a plurality of bus access units associated respectively with user terminals 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 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 for storing a packet from the data bus and forwarding it to the associated user terminal. An address filter 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 is connected to the receive-not-ready bus for terminating the transmission of a packet in response to the receive-not-ready signal.