Jeremy's IT Lab CCNA Course: Lesson 3

Overview

• Aimed to cover everything needed to pass the CCNA exam.
• Focus on two networking models: OSI Model and TCP/IP Suite.
• Includes supplementary materials like quizzes, flashcards, and practice labs.

Networking Models

What is a Networking Model?

• Categorizes and provides structure for networking protocols and standards.
• Networking protocols are logical rules for communication between devices.

OSI Model

Introduction

• OSI stands for Open Systems Interconnection.
• A conceptual model used to standardize network communications.
• Divides network functions into 7 layers.

OSI Model Layers

1. Application Layer (Layer 7)

   • Closest to the end-user.
   • Interacts with software applications with communication components (e.g., web browsers).
   • Protocols: HTTP, HTTPS.

2. Presentation Layer (Layer 6)

   • Translates data between application and network formats.
   • Manages encryption and decryption.

3. Session Layer (Layer 5)

   • Controls dialogues (sessions) between communicating hosts.
   • Manages session establishment, management, and termination.

4. Transport Layer (Layer 4)

   • Segments and reassembles data for communication.
   • Provides host-to-host (end-to-end) communication.

5. Network Layer (Layer 3)

   • Provides logical addressing (e.g., IP addresses).
   • Responsible for path selection and routing.

6. Data Link Layer (Layer 2)

   • Ensures node-to-node data transfer and connectivity.
   • Detects and corrects errors from the physical layer.

7. Physical Layer (Layer 1)

   • Defines physical characteristics of the medium (e.g., cables, connectors).
   • Converts digital bits into signals.

Encapsulation Process

• Data is encapsulated and de-encapsulated through layers as it is transmitted and received.
• Terms: Segment (Layer 4), Packet (Layer 3), Frame (Layer 2).

TCP/IP Suite

Introduction

• Used in the Internet and modern networks.
• Developed by the U.S. Department of Defense.
• Similar structure to OSI but with fewer layers.

Comparison to OSI

• Application Layer in TCP/IP combines OSI's Application, Presentation, and Session layers.
• Transport Layer is present in both models.
• Network/Internet Layer maps to OSI's Network layer.
• Link Layer in TCP/IP model combines OSI's Data Link and Physical layers.

Practical Use

• TCP/IP is the actual model in use today.
• OSI terminology is still used for discussing network issues.

Key Concepts and Terms

• Protocol Data Unit (PDU): Generic term for Segment (Layer 4), Packet (Layer 3), Frame (Layer 2).
• Same-layer Interaction: Interaction between the same layer on different systems.
• Adjacent-layer Interaction: Interaction between adjacent layers on the same system.

Supplementary Materials

• Quizzes, flashcards, packet tracer labs.
• Acronyms for remembering OSI layers:
  • "All People Seem To Need Data Processing"
  • "Please Do Not Teach Students Pointless Acronyms"

Quiz Insights

• Focus on understanding OSI layers’ functions relevant to network engineering.
• Emphasize the difference in terminology between OSI and TCP/IP models.

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End Note:

• For better understanding and practice, explore supplementary materials and quizzes.
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