Computer Networks Overview

Course Information

• Course Title: Computer Skills & Programming Concepts I
• Course Code: UEC01 – PCD104 – PCC104 – HGCP101
• Lectures: 12
• Course Coordinator: Assoc. Prof. Mohamed Ismail Badawi

Lecture Content

• What is a Network?

  • A network is a connected system of objects or people.
  • A computer network is a collection of computers and other hardware devices connected together to allow users to share hardware, software, and data, and communicate electronically.
  • Computer networks are merging with telephone and other communications networks.

• Network Characteristics:

  • Wired vs. Wireless Networks
    • Wired networks use physical cables to connect devices.
    • Wireless networks use radio waves to connect devices.
  • Network Topologies: These describe how devices are arranged in the network.
    • Star Networks: All devices connect to a central device (e.g., server). If the center device fails, the network generally fails.
    • Bus Networks: Devices connect to a single central cable.
    • Mesh Networks: Multiple connections between devices allow for multiple data transmission paths.
  • Network Architectures:
    • Client-Server Networks: A dedicated server handles requests from clients (computers or devices connected to the network). The server typically has multiple hard drives and faster processing speed than clients.
    • Peer-to-Peer (P2P) Networks: No central server is used; content is shared directly between users. Every computer has an equal level of access.
  • Network Size and Coverage Area:
    • Personal Area Networks (PANs): Connect personal devices in a small, close-range geographic area.
    • Local Area Networks (LANs): Connect devices within a small geographic area.
    • Metropolitan Area Networks (MANs): Connect devices over a city or metropolitan area.
    • Wide Area Networks (WANs): Connect networks over a large geographic area using two or more LANs.

• Network Types

  • Images show examples of PANs, LANs, MANs, and WANs.

• Data Transmission Characteristics:

  • Bandwidth: The amount of data that can be transmitted over a communication link in a given time. Measured in bits per second (bps), kilobits per second (kbps), megabits per second (mbps), or gigabits per second (gbps).
  • Analog vs. Digital Signals: Digital signals use discrete states (0s and 1s), while analog signals use continuous waves.
  • Link Transmission Type:
    • Simplex: Data travels in only one direction. (e.g., television)
    • Half-Duplex: Data travels in both directions, but in one direction at a time. (e.g., bank teller)
    • Full-Duplex: Data travels in both directions simultaneously. (e.g., conversation)

• Networking Media:

  • Wired Networking Media:
    • Twisted-Pair Cable: Insulated wires twisted together used for telephone and network connections (LANs).
    • Coaxial Cable: Thick wire with insulation, commonly used for computer networks and cable television.
    • Fiber-Optic Cable: Transparent fibers carry data as light, used in high-speed communications.
  • Wireless Networking Media: Data is transmitted via radio signals.

• Networking Hardware

  • Network Adapter (NIC): Connects a computer to a network.
  • Modem: Enables a computer to communicate over analog networks.
  • Switch: Connects devices in a network but sends data only to the intended recipient.
  • Hub: Similar to a switch, but sends data to all recipients in the network.
  • Router: Connects multiple networks (e.g., LANs, WANs) and routes traffic over the Internet.