COSC-85-Lecture-1

Introduction to Data Communication and Networking

  • Overview of lecture on data communication and networking.

Data Communications

  • Definition: Transmission of digital data between computers.

  • Data: Information in agreed-upon format between parties.

  • Telecommunication: Communication over distances.

  • Visual: Example of two devices connected via cable.

Fundamental Characteristics of a Data Communication System

  • Delivery: Ensures data reaches the correct destination.

  • Accuracy: Data must be delivered accurately; errors render data unusable.

  • Timeliness: Data must be delivered promptly; late data is useless.

  • Jitter: Variability in packet arrival times; affects audio/video data delivery.

Components of Data Communication

  • Message: Information being communicated, such as text or audio.

  • Sender: The device sending the message (e.g., computer, phone).

  • Receiver: The device receiving the message (e.g., workstation, television).

  • Transmission Medium: The physical means for data transmission (e.g., wires, radio waves).

  • Protocol: Set of rules that govern communications; an agreement between devices.

Data Flow Modes

  • Simplex: Unidirectional communication (e.g., keyboards).

  • Half-Duplex: Alternating transmission; both can send/receive but not simultaneously (e.g., walkie-talkies).

  • Full-Duplex: Simultaneous transmission and reception (e.g., telephone conversations).

Networks

  • Network Definition: A set of connected devices that communicate.

  • Node: Any device that can send/receive data.

  • Distributed Processing: Division of tasks among multiple computers.

Network Performance Criteria

  • Performance Measurement:

    • Transit Time: How long it takes for a message to travel between devices.

    • Response Time: Time taken for a response after an inquiry.

    • Factors Affecting Performance: Number of users, type of medium, hardware capabilities, software efficiency.

Network Reliability and Security

  • Reliability Measurement: Frequency of failure, recovery time, robustness during catastrophes.

  • Security Issues:

    • Protecting data from unauthorized access, damage, and changes.

    • Recovery policies for data breaches.

Protocols in Data Communication

  • Protocol: Rules defining data communication (syntax, semantics, timing).

    • Syntax: Structure/format of the data.

    • Semantics: Meaning of data sections.

    • Timing: When and how fast data is sent.

Standards in Data Communication

  • Importance of Standards: Ensure open markets and interoperability.

  • Types of Standards:

    • De Facto: Widely used but not legally approved standards.

    • De Jure: Legally established standards by recognized bodies.

Physical Structures of Networks

  • Point-to-point: Dedicated link between two devices.

  • Multipoint: More than two devices sharing a single link.

Network Topology

  • Definition: Physical and logical arrangement of nodes.

  • Types of Topologies:

    • Mesh: Each device has point-to-point links to every other device.

    • Star: Devices connect to a central controller.

    • Bus: All nodes share a single communication line.

    • Ring: Each device connects only to two others, forming a circle.

    • Hybrid: Combination of different topologies.

Categories of Networks

  • Local Area Network (LAN): Small geographic area, cost-effective, high security.

  • Wide Area Network (WAN): Large geographical area coverage, via various transmission mediums.

  • Metropolitan Area Network (MAN): Intermediate size, usually within a city.