Chapter 3. Local-Area Networking Introduction

What You Will Learn

On completing this chapter, you will be able to:

  • Describe local-area networks (LANs)

  • Explain the functions of wide-area networks (WANs)

  • Describe analog and digital signals

  • Compare characteristics of different network cabling types

  • Draw simple network topologies

  • List the different types of hardware found in a LAN or a WAN

Local-area networks (LANs) send and receive data at rates much faster than can be transmitted over a telephone line; but the distances are limited, often to a few hundred feet maximum without using costly, long-range technologies, such as Long Reach Ethernet (LRE) or wave-division multiplexing (WDM). Because of distance limitations, LANs are found in small areas such as a floor in your office building or a home network. LANs are used to connect personal computers (PCs), network workstations, routers to the Internet, and other network devices, such as network-capable printers, as illustrated in Figure 3-1.

Figure 3-1. Desktop/Printer Implementation Without a LAN and with a LAN, Respectively


Users connected via a LAN can chat and share files, Internet access, and printer access. The alternative to a LAN is for each user to have his own printer and Internet access.

Three characteristics differentiate one LAN from another:

  • LANs can be configured in different topologies. Topology is the geometric arrangement of devices on the network. For example, devices can be arranged in a continuous ring, where each computer is a link in the chain, or in a star, where each computer is connected to the same central device.

  • LANs follow different protocols, which are the rules and specifications for sending and receiving data.

  • LANs are connected through different media. For example, with LANs, the media through which a signal is transmitted among devices is twisted-pair wire, coaxial cable, fiber-optic cable, or wireless.

Several small LANs can be connected together to create a single larger LAN within a building. If your LANs are in offices across the country, these LANs use connections provided by a network service provider to create a wide-area network (WAN).