Computer Networks and Their Effects

Course Curriculum Objectives

• Primary Topics covered in Network Curriculum:

  • Computer Networks fundamentals and definitions.
  • Network Routers and routing principles.
  • Common network hardware devices:
  • Network Interface Cards (NICs)
  • Hubs
  • Switches
  • Bridges
  • Wireless communication technologies:
  • Wi-Fi
  • Bluetooth
  • Cloud computing architectures and models.
  • Network classifications by scope and ownership:
  • Intranets
  • Extranets
  • The Internet
  • Network topology types:
  • Local Area Networks (LANs)
  • Wireless Local Area Networks (WLANs)
  • Wide Area Networks (WANs)

• Network Issues, Security, and Communication:

  • Network security principles (including password creation strategies and authentication types).
  • Anti-malware software solutions and virus defense mechanisms.
  • Electronic conferencing tools and methods.

• General Context:

  • Modern computing relies heavily on networks; most individual computers are connected either to small local networks (such as home networks) or extensive enterprise infrastructures to facilitate resource sharing (printers, software applications, and files).
  • The Internet represents the largest global computer network in existence.

Fundamentals of Computer Networks

• Definition of a Computer Network:

  • A computer network consists of two or more computers or electronic devices (such as printers, scanners, or servers) that are linked or connected together for specific functional purposes.
  • The main purpose of establishing a computer network is to share resources, including information/data, hardware components, and software applications.

• Network Architectures:

  • Simple Network: A basic point-to-point connection where two devices (e.g., a laptop and a desktop computer paired with a direct printer connection) interact with one another.

• Complex Network: An enterprise or multi-device network setup featuring a centralized server, multiple client workstations, network switches, a wireless router, a modem connection, print servers, and external connectivity to the Internet cloud.

Transmission Media and Network Formation

• Connecting Media Types:

  • Networks are formed by linking computers through physical or wireless transmission media:
  • Cables: Includes copper-based Ethernet/LAN cables and Fibre Optic cables.
  • Radio Signals: Wireless frequencies utilized by technologies such as Wi-Fi and Bluetooth.
  • Telephone Lines: Legacy or digital copper lines used for telecommunications and data transit.
  • Satellites: Geostationary telecommunications satellites used for long-distance communication systems.

• Physical Network Cables:

  • Physical cables transmit data between nodes faster, more reliably, and with greater security compared to radio signals.
  • Ethernet / LAN Cable: The most common physical media connection in local area networks, utilizing copper wires with modular connectors (such as RJ45 connectors).

• Fibre Optic Cable: Uses glass or plastic strands to transmit data signals in the form of light pulses, offering significantly higher data transmission speeds over long distances without electromagnetic interference.

• Wireless Transmission:
  • Radio Signal Transmission: Electromagnetic energy converted into radio waves transmitted between broadcasting and receiving antennas.

• Satellite Communication:
  • Utilizes ground station transmitting antennas that send uplink signals to geostationary satellites positioned at an altitude of approximately $36000\,\text{km}$ above Earth.
  • Satellites receive, amplify, and retransmit signals via a downlink to receiving ground antennas.

Advantages and Disadvantages of Computer Networks

• Advantages of Computer Networks:

  • Resource Sharing: Hardware equipment such as printers, plotters, and scanners can be shared among multiple network users, significantly reducing capital expenditure costs.
  • Remote Data Access: Files and documents can be transmitted, synchronized, and shared remotely across workstations.
  • Streamlined Communication: Facilitates rapid communication between peers on the network via email, messaging, and conferencing tools.
  • Location Independence: Enables users to access centrally stored files or perform work tasks seamlessly from different physical locations.
  • Internet Access Infrastructure: Forms the core infrastructure underlying global communications and online services.

• Disadvantages of Computer Networks:

  • Single Point Failure Risk: Hardware or system failures in central network infrastructure (e.g., core switches or servers) can halt operational productivity.
  • Rapid Malware Propagation: Malware and computer viruses spread rapidly across interconnected network nodes.
  • Vulnerability to Cyber Crime: Unsecured network links expose connected systems to unauthorized access and hacking.
  • Resource Contention: Heavy concurrent reliance on shared peripherals (such as print queues) creates operational bottlenecks and delays.
  • Internet Security Threats: Connecting to global public networks exposes users to privacy violations, data theft, and identity fraud.

Classification of Computers in Network Systems

• Stand-Alone Computer:

  • An independent, isolated computer system that is not connected to any network or external computing devices.

• Network Computer:

  • Any computer connected into a network architecture, capable of sending, receiving, and sharing data.

• Client-Server Roles:

  • Client (Peer): An individual host computer on a network that requests services, applications, or files from a server.
  • Server: A dedicated high-performance computing system designed to process requests and deliver centralized resources or services to client systems on the network.
  • Server Types:
  • File Server: Centralizes file storage, access permissions, and data retrieval.
  • Print Server: Manages print requests and coordinates queues across shared printers.
  • Application Server: Hosts and executes software applications for network client machines.
  • Proxy Server: Acts as an intermediary gateway between local client computers and external servers/networks for filter management and security.
  • Web Server: Hosts website content, serving web pages via HTTP/HTTPS protocols.

Dedicated Network Hardware Devices

• Essential Hardware Devices:

  • Cables (Ethernet/LAN and Fibre Optics)
  • Hub
  • Switch
  • Bridge
  • Router
  • Modem
  • Network Interface Card (NIC)

• Network Interface Card (NIC):

  • A hardware component installed inside a computer that enables it to connect physically or wirelessly to a network.

• The Network Hub:

  • Function: A central hardware unit that links multiple computers or network devices through physical connectivity ports.
  • Classification as a "Dumb" Device: A Hub is categorized as an unmanaged or "dumb" network device because it lacks intelligent routing or packet-filtering mechanisms.
  • Operational Behavior: When a Hub receives data packets on one port, it indiscriminately broadcasts (floods) those packets to every other port and connected device on the network, regardless of the designated destination address.