In telecommunication, a duplex communication system is a point-to-point system of 2 devices that may communicate with one another in each direction. These 2 forms of duplex communication systems exist in local area network environments:
half-duplex – a port will send data only if it’s not receiving data. In different words, it cannot send and receive data at the same time. Network hubs run in half-duplex mode in order to stop collisions. Since hubs are rare in modern LANs, the half-duplex system isn’t wide utilized in local area network networks any longer.
NOTE – every NIC and switch port has a duplex setting. For all links between hosts and switches, or between switches, the full-duplex mode should be used. However, for all links connected to a LAN hub, the half-duplex mode should be utilized in order to stop a duplex mismatch that could decrease network performance.