Computer Networks & Network Topologies (NaCCA B7.3.1)

A Computer Network is a collection of two or more computers and computing devices connected together using cables or wireless signals to share resources and communicate. • Why Do We Network Computers? 1. Sharing Hardware Resources: Instead of buying a separate printer or scanner for every computer, multiple users share one central network printer, saving schools thousands of cedis. 2. Sharing Software and Files: Teachers can place study notes in a shared folder on the main computer, and every student in the lab can open them without needing a USB drive. 3. Internet Sharing: A single high-speed broadband internet subscription can be shared across all school laptops simultaneously. 4. Fast Communication: Network users can send instant messages, emails, and notices to one another across classrooms or offices.

Networks are classified according to the physical distance they cover: • 1. Local Area Network (LAN): - Covers a small, limited geographical area, such as a single classroom, a school computer laboratory, a home, or one office building. - Speed: Very high data transfer speeds with low error rates. - Ownership: Privately owned and controlled by the school or organization. - Connection: Connected using Ethernet cables (twisted pair) or local Wi-Fi (WLAN). • 2. Wide Area Network (WAN): - Spans a vast geographical distance across entire cities, regions, countries, or the whole world. - Uses telecommunications satellites, microwave links, and undersea fiber optic cables. - The Internet is the supreme, largest Wide Area Network in human history!

Network Topology refers to the physical or geometric arrangement of computers and cables in a network: • 1. Star Topology (Most Popular in Modern Labs): - Every computer is connected individually to a central connection device called a Switch or Hub. - Advantage: If one computer cable breaks or gets unplugged, only that single computer goes offline; all other computers continue working normally! - Disadvantage: If the central switch/hub breaks, the entire network fails. • 2. Bus Topology: - All computers are connected in a line along a single shared central backbone cable with terminators at both ends. - Advantage: Simple to install and requires the least amount of cabling. - Disadvantage: If the main backbone cable breaks anywhere, the entire network shuts down immediately. • 3. Ring Topology: - Computers are connected in a closed circular loop. Data travels in one direction from computer to computer around the ring.

To build a functional computer network, specific hardware devices are required: • 1. Network Interface Card (NIC): - An internal chip or expansion card in every computer and phone that connects it to the network. • 2. Transmission Media (Cables & Wireless): - Twisted Pair (Ethernet / RJ-45) Cables: Blue or grey cables that plug into computer network ports. - Wi-Fi (Wireless): Connects laptops and smartphones using radio signals without physical cables. • 3. Switch / Hub: - The central junction box in a Star network that receives data packets and forwards them to the correct computer. • 4. Router: - An intelligent device that connects a local network (LAN) to an external network like the Internet.