local area network

local area network
Name	Local Area Network
Caption	A conceptual diagram of a LAN connecting computers, printers, and a server.
Invented	1970s
Industry	Information technology, Telecommunications
Related	Metropolitan area network, Wide area network, Personal area network

local area network. A local area network is a computer network that interconnects devices within a limited geographical area such as a residence, school, laboratory, university campus, or office building. By contrast, a wide area network covers a broader geographic distance, often using leased telecommunication circuits. The defining characteristics of these networks include higher data transfer rates, smaller geographic scope, and the absence of a need for leased telecommunication lines. The rise of personal computers and workstations in the late 20th century, championed by companies like Digital Equipment Corporation and Xerox PARC, drove the initial development and standardization of this technology.

Definition and purpose

The primary purpose is to enable resource sharing and communication between connected devices within a confined location. This allows multiple users to access common peripherals like printers and scanners, share files stored on a central file server, and facilitate internal communication through tools like instant messaging and email. In business environments, they are fundamental for running collaborative applications such as customer relationship management software and enterprise resource planning systems from vendors like SAP SE and Oracle Corporation. Educational institutions like Massachusetts Institute of Technology and corporate campuses such as the Microsoft headquarters in Redmond rely heavily on these networks for daily operations and research collaboration.

Technical components

The physical infrastructure consists of several key hardware elements. Network interface cards, produced by manufacturers like Intel and Broadcom, are installed in each device to provide a connection point. These devices are interconnected via cabling, historically coaxial cable but now predominantly twisted pair or fiber-optic cable, or through wireless access points using standards from the Institute of Electrical and Electronics Engineers. Central connecting devices include switches and hubs, which manage data traffic, and routers, which often provide a gateway to external networks like the Internet. Backbone segments may utilize high-speed technologies from companies like Cisco Systems.

Network topologies

The physical or logical layout of connected devices defines the network's topology. The bus topology, used in early implementations like those from 3Com, connects all devices to a single central cable. The star topology, now the most common, connects all devices to a central switch, a design popularized by standards from the Telecommunications Industry Association. The ring topology connects devices in a closed loop, a method utilized in legacy systems like IBM's Token Ring. More complex hybrid topologies, such as mesh networks, are employed in demanding environments like stock exchanges such as the New York Stock Exchange or research facilities at CERN.

Communication protocols

Protocols are the standardized rules that govern data communication across the network. The IEEE 802.3 standard, commonly known as Ethernet, is the dominant family of protocols for wired connections, originally developed at Xerox PARC. For wireless connections, the IEEE 802.11 family of standards, marketed as Wi-Fi, is ubiquitous. The Internet protocol suite, particularly the Transmission Control Protocol and the Internet Protocol, provides the fundamental addressing and routing mechanisms for data packets. Other historical protocols include the ARCNET standard from Datapoint Corporation and AppleTalk from Apple Inc..

Security considerations

Protecting the network from unauthorized access and threats is a critical concern. A fundamental defense is the firewall, often integrated into routers from vendors like Juniper Networks. Network segmentation using virtual LANs can isolate sensitive departments, such as finance or human resources. Strong authentication protocols like those developed by the Internet Engineering Task Force and encryption standards such as WPA3 for wireless networks are essential. Organizations must also defend against malware attacks, data breaches like those investigated by the Federal Bureau of Investigation, and internal threats, often guided by frameworks from the National Institute of Standards and Technology.

Applications and use cases

These networks are foundational to modern digital infrastructure in nearly every sector. In corporate offices, they enable access to shared databases, voice over IP phone systems, and video conferencing with platforms like Zoom Video Communications. Manufacturing plants use them for industrial control systems and to connect machinery on the factory floor. Hospitals and clinics, such as those within the National Health Service, rely on them for patient record systems and medical imaging equipment. Academic institutions like Stanford University use them for campus-wide internet access, library systems, and collaborative research projects, often connecting to wider networks like Internet2.

Category:Computer networking Category:Digital technology