Summary

12 IT Essentials: PC Harware and Software Companion Guiderepresents the number of cars that can travel on the highway at the same time. An eight-lanehighway can handle four times the number of cars that a two-lane highway can.Figure 8-7Highway AnalogyThe data that is transmitted over the network can flow using one of three modes: simplex,half duplex, or full duplex:■■■Simplex: Simplex, also called unidirectional, is a single one-way transmission. Anexample of simplex transmission is the signal that is sent from a TV station to your TV.Half duplex: When data flows in one direction at a time, this is known as half duplex.With half duplex, the communications channel allows alternating transmission in twodirections, but not in both directions simultaneously. Two-way radios, such as policeand emergency communications mobile radios, work with half-duplex transmissions.When you press the button on the microphone to transmit, you cannot hear the personon the other end. If people at both ends try to talk at the same time, neither transmissiongets through.Full duplex: When data flows in both directions at the same time, this is known as fullduplex. Although the data flows in both directions, the bandwidth is measured in onlyone direction. A network cable with 100 Mbps in full-duplex mode has a bandwidth of100 Mbps. A telephone conversation is an example of full-duplex communication. Bothpeople can talk and be heard at the same time.Full-duplex networking technology increases network performance because data can be sentand received at the same time. Broadband technology allows multiple signals to travel onthe same wire simultaneously. Broadband technologies, such as digital subscriber line(DSL) and cable, operate in full-duplex mode. With a DSL connection, for example, userscan download data to their computer and talk on the telephone at the same time.