Computer Communications

Computer Communications

  • Definition: Communication is a fundamental human desire, evolving from primitive methods like drum codes and smoke signals to electronic communications today.
  • Development:
    • Primitive methods for long-distance information exchange led to modern computer networking, which began to take shape around 1965.
    • Computers can transmit data across the world almost instantaneously using telephone, microwaves, or radio links.

Networking Overview

  • Computer Network: A system consisting of interconnected nodes designed to share data, hardware, and software.
  • Connecting mediums: Copper wires, fiber optic cables, microwaves, infrared, and satellite links.

Reasons for Networking

  1. Sharing Resources:

    • Allows multiple PCs to connect to a single expensive resource (e.g., line printer).

  2. Sharing Information:

    • Accessing information on one computer from others in the network helps avoid duplication of data files.

  3. Communication:

    • Facilitates messaging between connected PCs for business operations and updates.

Applications of Networks

  • Various Areas of Employment:
    • Electronic Data Interchange
    • Tele-conferencing
    • Cellular Telephones
    • Cable Television
    • Financial Services (marketing, sales)
    • Reservation systems for airlines, trains, theatres, buses
    • Telemedicine
    • ATMs
    • Internet Banking

Benefits of Networking

  1. Personal Communications:

    • Effective handling and management of personal communications.

  2. Multi-user Access:

    • Multiple users can access important programs and data simultaneously.

  3. Data Management:

    • Users can store critical data on shared storage devices, ensuring its safety.

  4. Equipment Sharing:

    • Reduces costs by allowing shared access to expensive equipment.

  5. Data Transfer Security:

    • Ensures safe, secure, and reliable data transfers across the network.

Types of Networks

  • The main types include:
    1. Local Area Network (LAN)
    2. Metropolitan Area Network (MAN)
    3. Wide Area Network (WAN)

Local Area Network (LAN)

  • Definition: Connects systems/devices within a single building or nearby buildings, usually not utilizing the telephone network.
  • Connection methods:
    • Wired: Twisted pairs, coaxial cables, fiber optic cables.
    • Wireless: Infrared or radio waves.
  • Performance:
    • Often more efficient than wireless, which is slower but useful for portability.

Network Topology

  • Definition: The layout/structure of communication channels connecting various computers (nodes).
  • Factors influencing topology choice:
    • Type of nodes
    • Expected performance
    • Type of wiring used
    • Cost considerations
  • Common Topologies:
    1. Star
    2. Ring
    3. Bus
    4. Hybrid
    5. FDDI

Star Network

  • Structure: All devices connect to a central hub (file server or host computer) via Unshielded Twisted Pair (UTP) cables.

Ring Network

  • Structure: Devices are connected in a continuous loop; data is passed around the ring in one direction, with each node acting as a repeater.
  • Characteristics: No central host or server.

Bus Network

  • Structure: All devices connect to a common cable (the bus).
  • Data Transmission: It is bidirectional and does not require a central server.