Day-17: Half & Full Duplex .

By | May 22, 2022

Duplex in networking often refers to a point-to-point communication system and its ability to send and receive information. Bi-directional network data transmission can be achieved by using a full-duplex device. Data can move in two directions, but not simultaneously when it is in half-duplex mode. The term duplex is used to describe the capability of sending and receiving data simultaneously.

Half Duplex.

A half-duplex system can be compared to the “push-to-talk” nature of a walkie-talkie. When the button is pressed, the receiver is turned off, and the transmitter is activated. When the button is released, the transmitter is turned off, and the receiver is turned back on. The device cannot transmit and receive simultaneously. A full-duplex system is like talking on the telephone, in which both parties can speak and listen at the same time.

In Half Duplex, it cannot send and receive data at the same time. Network hubs run in half-duplex mode in order to prevent collisions. Since hubs are rare in modern LANs, the half-duplex system is not widely used in Ethernet networks anymore.

Full Duplex.

In a full-duplex network, data can be transmitted simultaneously on a signal carrier on both ends. For example, on a local area network with a technology that allows full-duplex transmission, one workstation can send data on the line while another workstation receives it.

In Full Duplex, all nodes can send and receive on their port at the same time. There are no collisions in full-duplex mode, but the host NIC and the switch port must support the full-duplex mode. Full-duplex Ethernet uses two pairs of wires at the same time instead of a single wire pair like half-duplex.

Recommended Duplex Settings.

Each 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 used in order to prevent a duplex mismatch that could decrease network performance.

Diplex can be configured auto or manually between the devices. But it’s recommended to set the speed and duplex manually.

Note:If you want to configure the duplex and speed as AUTO then the auto-negotiation must be ON in both end devices.

For better performances, you have to configure the duplex as full and the speed must be maximum based on your transmission media such as Fast Ethernet, Gigabit Ethernet, 10G ethernet, etc.

There should not be a miss-match of duplex and speed.

How to set the Speed and duplex setting on your computer?

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