Complete CCNA Course - Lesson 3: Networking Models

Introduction

• Presented by Jeremy from Jeremy's IT Lab
• Focus: CCNA preparation, including OSI Model and TCP/IP Suite
• Free resources: Anki flashcards and quiz at end of video

Networking Models Overview

• Networking Models categorize and provide structure for networking protocols and standards.
• Networking Protocol: A set of rules for network devices/software interaction (e.g. Ethernet).

Importance of Networking Standards

• Without standards, devices from different manufacturers cannot communicate (e.g. Dell PCs vs. Apple iMacs).

OSI Model

• OSI: Open Systems Interconnection Model
• Developed in late 1970s and early 1980s by ISO (International Organization for Standardization).
• 7 Layers:
  1. Layer 1: Physical Layer
     • Standards for cables & interfaces (examples include electrical signals).
  2. Layer 2: Data Link Layer
     • Node-to-node connectivity; error detection.
  3. Layer 3: Network Layer
     • Logical addressing (IP addresses), path selection; routers operate here.
  4. Layer 4: Transport Layer
     • Segments/reassembles data; ensures reliable transmission.
  5. Layer 5: Session Layer
     • Manages sessions between applications (e.g. establishes, manages, and terminates sessions).
  6. Layer 6: Presentation Layer
     • Translates data formats, including encryption/decryption.
  7. Layer 7: Application Layer
     • Interacts directly with application software (e.g. web browsers using HTTP/HTTPS).

Data Encapsulation and De-encapsulation

• Encapsulation: Process of adding headers at each OSI layer as data is prepared to be sent.
• De-encapsulation: The reverse process where headers are stripped off at the receiving end.
• Protocol Data Units (PDUs):
  • Bit: Layer 1 (Physical)
  • Frame: Layer 2 (Data Link)
  • Packet: Layer 3 (Network)
  • Segment: Layer 4 (Transport)

TCP/IP Suite

• TCP/IP: A networking model similar to OSI but with fewer layers; in actual use today.
• Developed by DARPA (Defense Advanced Research Projects Agency).
• Layers:
  • Application Layer (combines OSI's Application, Presentation, and Session)
  • Transport Layer (same as OSI)
  • Internet Layer (equivalent to OSI's Network Layer)
  • Link Layer (combines OSI's Data Link and Physical layers)

Key Differences between OSI and TCP/IP

• OSI is theoretical; TCP/IP is practical and widely implemented.
• Terminology differences: Some layers may have varying names across different interpretations.

Important Concepts

• Encapsulation and De-encapsulation are essential for data communication.
• Same-layer interaction: Interaction at the same layer between two systems (e.g. application layers).
• Adjacent-layer interaction: Interaction between different layers of the model.

Quiz

• Review of concepts with interactive questions at the end of the video.
• Encouraged engagement through comments and sharing of videos.

Conclusion

• Importance of understanding OSI vs. TCP/IP for networking professionals.
• Resources for further study: Anki flashcards, Packet Tracer lab, and cryptocurrency donation options available.