Chapter_1_-_Introduction__1_

Chapter 1: Introduction to Computer Networks

Learning Objectives

  • Understand what a computer network is and its purpose.

  • Explain and distinguish between types of networks from different perspectives.

  • Identify and determine the necessary hardware components for installing a computer network.

What is a Computer Network?

  • A network consists of two or more connected devices (nodes) that can communicate for resource sharing.

  • The term "node" or "host" refers to any device on the network, including computers, mobile devices, printers, routers, switches, etc.

Characteristics of a Computer Network

Connectivity

  • Nodes can connect through:

    • Wired connections (network cables, telephone lines)

    • Wireless connections (radio waves, microwaves, satellites, infrared light beams)

Communication

  • Data transfer occurs through communication protocols (e.g. TCP/IP, HTTP, FTP).

Resource Sharing

  • Nodes share:

    • Hardware resources (printers, disc drives)

    • Software resources (files, programs, folders)

Understanding Networking Jobs

Network Administrator Responsibilities

  • Create, maintain and remove user accounts.

  • Manage network security policies.

  • Add new networking equipment (servers, routers, hubs, switches) and manage this equipment.

  • Monitor network hardware and software for problems and utilization levels for planning upgrades.

  • Troubleshoot network issues.

  • Ensure backups of administrative accounts and passwords.

Network Engineer Responsibilities

  • Involved deeply in network functions (bits and bytes).

  • Handle advanced network troubleshooting beyond network administrator capabilities.

Network Designer Responsibilities

  • Work with organizations selling/supporting large networks.

  • Understand business requirements and available networking products, as well as how they interact.

Other Network-Related Jobs

  • Include roles such as database administrators, web designers, email administrators, etc.

Types of Networks

  • Classified from different perspectives:

    1. Transmission Media: Wired (Twisted-pair, coaxial, fiber-optic) and Wireless media.

    2. Network Size: Local Area Network (LAN), Metropolitan Area Network (MAN), Wide Area Network (WAN).

    3. Network Architecture: Peer-to-Peer and Client/Server.

    4. Network Topology: Bus, Star, Ring, Mesh.

Transmission Media

Wired Transmission Media

  • Twisted Pair Cables:

    • Cheapest and widely used; good for short distances (up to 100m).

    • Contains four twisted pairs of copper wires; terminated with RJ-45 connectors.

  • Coaxial Cables:

    • Better interference resistance; used for TV cables.

    • Requires repeaters for digital transmission over longer distances; terminated with BNC connectors.

  • Fiber Optic Cables:

    • Very high bandwidth and low signal degradation; can carry hundreds of Gbps over long distances.

    • Typically terminated with LC, FC, SC, or ST connectors.

Wireless Transmission Media

  • Wireless Signals: Utilize electromagnetic waves to communicate without a physical medium.

  • Commonly use microwaves, radio waves, and infrared waves for network communication.

Network Size Classifications

  • Local Area Network (LAN): Small geographic regions (e.g. room, building).

  • Metropolitan Area Network (MAN): Larger geographic regions (e.g. town, small city).

  • Wide Area Network (WAN): Broad geographic regions (e.g. across countries); the Internet is a primary example.

Network Architecture

Peer-to-Peer Networks

  • Equal devices where each can function as both client and server.

  • Each peer manages its own resources and security.

Client/Server Networks

  • Centralized servers provide resources to connected clients.

  • Clients request and receive information from servers.

Network Topology

Bus Topology

  • All nodes connected to a single communication cable.

  • Advantages: cheap, easy to install.

  • Disadvantages: limited nodes, network failure if cable is damaged.

Star Topology

  • Nodes connected through a central hub/switch.

  • Advantages: easy to add devices, single point failure does not affect entire network if workstation fails.

  • Disadvantages: if hub fails, entire network goes down.

Ring Topology

  • Nodes connected in a closed loop, messages travel in one direction.

  • Advantages: orderly transmission, good communication over long distances.

  • Disadvantages: single node failure affects the entire network.

Mesh Topology

  • Each node connected to every other node; offers high fault tolerance.

  • Advantages: reliable data routing; existing paths if one cable breaks.

  • Disadvantages: complex design, expensive to install.

Network Hardware Components

  • Essential components for physically installing a network include:

    • Network Interface Cards

    • Cables/Links

    • Connectivity Devices

Research Activity Suggestions

  1. Explain different categories of UTP cables (CAT1, CAT2, ..., CAT6) and identify commonly used types.

  2. Explore additional network topologies beyond those covered in the chapter.

  3. Establish a peer-to-peer network on your Operating System and manage resource sharing.