Introduction to Computer Networks

• Computer networks enable sending messages with various media to multiple people, connecting to international information sources, holding remote conferences, and facilitating E-Learning, E-Commerce, and E-Government.
• These capabilities result from integrating communication and computer technologies to create computer networks.

Network Definition

• A network connects two or more computers to share resources like printers or CDs, exchange files, and facilitate electronic communication.
• Network connections can be wired or wireless, using cables, telephone lines, radio waves, satellites, or infrared light beams.

Benefits of Computer Networks

• File sharing is simplified, allowing data access across different users or remote access.
• Resource sharing reduces costs by enabling shared network peripherals like printers and software.
• Information sharing and communication become easier.
• Business efficiency is improved, illustrated by avoiding multiple data entries through networked access to a common database preventing errors and saving time.

Computer Network Components

• A computer network comprises several components, each with its own function.
• Key components are: a server, clients, transmission media, network interface card, peripherals, communication switches, and a network operating system.

Computer Network Component Details

• Servers store shared files, programs, and the network operating system providing access to network resources.
• Servers are fast with high processing speeds and large storage capacity.
• Clients, or workstations, request and receive services from servers to access and use network resources.
• Transmission media carry data between devices in a network.
• Transmission media can be guided, like coaxial or fiber optic cables, or unguided, like microwaves and infra-red waves.
• A network interface card (NIC) on each computer prepares/formats, sends, and receives data, controlling its flow.
• Peripherals are hardware resources like printers and scanners provided by servers.
• Communication switches, such as routers, hubs, switches, and repeaters, connect devices as middleware to bind network media.
• Network operating systems are programs on computers/servers enabling communication over the network.

Computer Network Types

• Computer networks are categorized by size, falling into three main types.
• The three types are: LANs, MANs, and WANs.

LAN (Local Area Network)

• LANs connect computers in a small area like a building or office.
• LAN data transfers occur at extremely fast rates.
• LANs provide a high level of security.

MAN (Metropolitan Area Network)

• MANs cover larger geographic areas by interconnecting LANs.
• MANs connect various LANs.
• MANs have a higher range than LANs.

WAN (Wide Area Network)

• WANs extend over large geographical areas like states or countries.
• WANs are larger than LANs.
• WANs span large geographical areas via telephone lines, fiber optic cables, or satellite links.
• The internet is one of the largest WANs worldwide.
• WANs are widely used in business, government, and education.

Network Protocols

• A network protocol establishes rules that govern data transmission, device communication, data sending, and error management in a network.

Types of Protocols

• Transmission Control Protocol (TCP) is a common communication protocol that divides messages into packets for transmission and reassembly.
• Internet Protocol (IP) is designed for addressing and is often used with TCP; IP addresses in packets route them to the destination system through different nodes.
• File Transfer Protocol (FTP) enables file sharing between hosts using a connection made for the file transfer.
• Hyper Text Transfer Protocol (HTTP) is used for hypertext transfer in the World Wide Web via a request/response model.
• With HTTP the client sends a request to the server, which is processed before a response is sent back.