When talking about duplex modes, you are referring to how data is transmitted on a network. The duplex mode being used basically determines if the switch or device uses one-way or two-way communication. Most switches allow you to choose which duplex mode to use. For example, PowerConnect 3324/3348 series switches support both multiple duplex modes.

There are three different duplex modes:

  • Simplex
  • Half-duplex
  • Full duplex

Most networking devices will use either half-duplex or full-duplex.

Simplex Mode is used at the session layer of the Open Systems Interconnect (OSI) model. When a device is functioning in Simplex mode one node sends data only and another node receives only. In other words, communication is only one-way.

With Half-duplex communication is two-way, but only one direction at a time. In other words, only one node can send at a time. Each node then takes a turn sending and receiving data.

The third duplex mode is known as Full duplex. Communication is two-way and simultaneous. This means that both nodes can send and receive at the same time.

Most LANs will use half-duplex or full duplex. Half-duplex communication is similar to using a CBC radio. Only one person is allowed to communicate at once. Where as full-duplex communication is similar to communicating using a telephone. Each person can communicate simultaneously.

[tags]diana huggins,lan,duplex mode,data transmit,simplex mode[/tags]