Introduction to Local Area Network (LAN)

 

Introduction to Local Area Network (LAN)

What is a LAN?

A Local Area Network (LAN) is a network that connects devices within a limited geographical area such as:

  • A home
  • An office
  • A building
  • A school campus

A LAN is usually privately owned and managed by an individual or organization.

Definition

A LAN is a network that interconnects hosts in a single office, building, or campus to enable communication and resource sharing.

Characteristics of a LAN

1. Limited Geographical Area

A LAN covers a small area compared to larger networks like WANs.

Examples:

  • Computer lab in a college
  • Office network in a company
  • Home Wi-Fi network

2. High-Speed Communication

Since devices are located close to each other, LANs provide:

  • Faster data transfer
  • Lower delay
  • Efficient communication

3. Private Ownership

LANs are generally owned and maintained by:

  • Schools
  • Companies
  • Universities
  • Home users

4. Resource Sharing

LANs allow multiple users to share:

  • Printers
  • Files
  • Internet connection
  • Storage devices

Hosts in a LAN

The devices connected in a LAN are called hosts.

Examples of hosts:

  • PCs
  • Laptops
  • Smartphones
  • Servers
  • Printers

Each host in a LAN has a unique identifier called an address.

When a host sends a packet:

  • The packet contains the source address
  • And the destination address

This helps the network deliver data to the correct device.

Traditional LAN Structure

Earlier LANs used a common shared cable.



In this method:

  • Every packet was received by all hosts
  • Only the intended recipient accepted the packet
  • Other devices discarded it

Limitation

This caused:

  • Heavy traffic
  • Reduced efficiency
  • Lower performance

Modern LAN Structure Using Switches

Today, most LANs use a switch.



Pic courtesy:Computer Networks: A Top-Down Approach Behrouz A Forouzan McGraw Hill SIE, 2017

A switch:

  • Reads the destination address
  • Sends the packet only to the intended device
  • Reduces unnecessary traffic
  • Improves network performance

Advantages of Using a Switch

Reduced Traffic

Packets are not broadcast to every host.

Better Performance

Multiple devices can communicate simultaneously.

Efficient Communication

Data reaches the correct destination quickly.

Size of a LAN

A LAN can be:

  • Very small → two computers and a printer
  • Very large → entire company network with audio/video devices

There is no fixed minimum or maximum number of hosts in a LAN.

Modern Use of LANs

Earlier, LANs were often used independently for local resource sharing.

Today, LANs are commonly connected to:

  • Other LANs
  • Wide Area Networks (WANs)
  • The Internet

This enables communication on a much larger scale.

Real-Life Examples of LAN

  • College computer laboratory
  • Office network
  • Home Wi-Fi system
  • Library network
  • Banking branch network

Summary

A Local Area Network (LAN) is a privately owned network that connects devices within a limited area such as a home, office, or campus. Modern LANs use switches to efficiently transfer data between hosts and support resource sharing and high-speed communication.

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