Lecture Notes: Networking Technologies and the OSI Model

Overview of the OSI Model

• OSI Model: Stands for Open Systems Interconnection Model.
  • Developed by the International Standards Organization in the early 1980s.
  • A seven-layer model used universally to discuss and understand networking technologies.
  • Although not perfect, it is an essential conceptual tool.
• Purpose: Helps in understanding and discussing how different networking technologies fit together.

Layers of the OSI Model

• Layer 1: Physical Layer

  • Deals with the physical means of encoding information.
  • Methods of encoding:
    • Manchester Code: A form of encoding discussed in previous videos.
    • NRZ (Non-Return Zero): Another encoding method not extensively covered.
    • QAM (Quadrature Amplitude Modulation): To be possibly covered in more advanced topics.

• Layer 2: Data Link Layer

  • Focuses on framing and frame formats.
  • Technologies discussed include:
    • Ethernet Framing:
      • Uses preamble and inner frame gap to denote frames.
    • HDLC (High-Level Data Link Control):
      • Uses flag bytes to denote frames.
  • Frame Formats:
    • Ethernet Logical Link Control: The format discussed in detail.
    • PPP (Point-to-Point Protocol) Logical Link Control: Also covered.

Future Topics

• Future content will cover layers 3 through 7, with continued reference back to the OSI model.
• Emphasis on understanding how each layer depends on the layers below it and integrates with them.