Half duplex and full duplex
In telecommunications, a two-sided communication system is a point-to-point system of two devices that can communicate with each other in both directions. Both types of duplex communication systems are available in Ethernet environments:
Half duplex - A port can send data only if it does not receive data. In other words, it can not send and receive data at the same time. Network hubs operate in half-duplex mode to avoid collisions. Because hubs are rare in modern LANs, the half-duplex system is no longer widely used in Ethernet networks.
Full duplex - all nodes can send and receive simultaneously on their port. There is no full-duplex collision, but the host network adapter and the switch port must support full duplex mode. Ethernet full duplex uses two pairs of cables instead of a single pair of cables, such as half duplex.
Each network adapter and switch port have a duplex setting. All connections between hosts and switches or between switches must use full duplex mode. However, all connections connected to a LAN concentrator must use half-duplex mode to avoid duplex incompatibility, which can affect network performance.
On Windows, you can specify duplex settings in the Network Adapter Properties window:
