Local Area Network (LAN)

A local area network is a group of computers that communicate through a network cable or wireless connections. Unlike the similar wide area network, local area networks, commonly referred to as LANs, cover only a small area. In most cases, this area is confined to a room or building. Local area networks are commonly used in offices, schools, and government buildings.

Introduction to Local Area Networks

In order for computers to communicate, they need a way to transfer data from one machine to another. In some cases, this is accomplished via an Internet connection. In others, computers share data through a local area network. This data sharing may take place through a variety of means, including Ethernet cables, token ring protocols, Wi-Fi, Fiber Distributed Data Interfaces (FDDI), and ARCNET. The most common interfaces are Ethernet cables and Wi-Fi. Modern LANs commonly use Ethernet switches for wired connections and Wi-Fi access points for wireless connections.

To create a local area network with Ethernet cables, each computer must have a properly installed Ethernet port. An Ethernet port is a physical receiver for an Ethernet cable attached to the computer’s motherboard. A computer lacking an Ethernet port can have one installed. Alternatively, a temporary external Ethernet port may be installed through a USB slot.

While computers can be connected directly from Ethernet port to Ethernet port, it is impractical to connect a large number of computers in this fashion. It would require each computer to have a massive number of Ethernet ports to support any type of large network. Instead, Ethernet-based networks generally use a switch. A network switch is a hardware piece to which multiple machines on the network can be connected. This switch helps direct communication between machines on the network. Switches often have large numbers of ports to allow multiple machines to exist simultaneously on the network. In modern home and small-office networks, a router often includes a built-in Ethernet switch and wireless access point.

Wireless local area networks are possible using Wi-Fi. Initially, these networks were so expensive to set up that they were used only in rare situations where wiring was impossible. However, with the increased prevalence of Wi-Fi and wireless routers, this networking option has become much more affordable. In 2024, the Wi-Fi Alliance introduced Wi-Fi CERTIFIED 7, reflecting continued development of wireless LAN technology for higher performance and lower latency. Wireless LANs allow any device within the network’s range to connect and disconnect simply by manipulating the settings on the device. They also allow users of mobile devices—such as smartphones, tablets, and laptop computers—to remain active on the LAN while moving throughout a facility.

A token ring network is a type of local area network designed to avoid data collisions by passing a token among connected devices. It used a different access method from Ethernet and was most commonly associated with wired LANs. Token ring networks used specialized connection equipment to link computers in a logical ring. Only the device holding the token could transmit data, which helped prevent devices from sending data at the same time. Some token ring systems included a backup ring or fault-tolerant design in case part of the network failed. An FDDI network is a fiber-optic LAN technology that uses token passing and a dual-ring design. It uses ANSI and ISO standards for transmission on specialized fiber-optic cables. Unlike normal LANs, these networks can stretch over city blocks, and they can handle download speeds of 100 megabits per second. Many FDDI networks are made up of two token rings.

Why Use a Local Area Network?

Local area networks provide people, businesses, and governments with many advantages. They allow networks of computers to share expensive machines—such as copiers, scanners, and printers—so that businesses do not have to buy multiples of each machine. They also allow Internet services to be shared across the network, so that one powerful connection can supply large numbers of machines with online access.

Local area networks may be used to share critical information among machines without the need to copy the information from one machine to the others. Users may edit and access information kept in a database simultaneously. Local area networks can also be used to copy applications and programs to each machine and to set up periodic backups of every machine on the network. Lastly, local area networks may be used to set up internal messaging services and intranet pages. These pages and messaging services would appear similar to other Internet websites and messaging systems. However, they would only be available to machines directly connected to the LAN or to users with authorized remote access. This provides companies with an added layer of protection as it would be difficult for an outsider to hack into these services because that person would need to get access to the LAN.

Of course, local area networks do have disadvantages. A hacker who gains access to a private network could easily view or download many important company files. Additionally, if a virus, Trojan, or other form of malware infects one computer on the network, the malware will quickly spread to every other device connected to the network. For this reason, security experts recommend setting up LANs with built-in security protocols, such as firewalls, access controls, network segmentation, and authentication.

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