647  Layered Network Models

647.1 Overview

Layered network models are the foundation of all network communication, dividing complex networking tasks into manageable, independent layers. This section covers the theoretical OSI model, the practical TCP/IP model, addressing schemes, and hands-on implementation.

OSI 7-layer reference model showing from bottom to top: Physical, Data Link, Network, Transport, Session, Presentation, and Application layers with functions of each layer

OSI 7-layer reference model

OSI 7-layer reference model showing from bottom to top: Physical, Data Link, Network, Transport, Session, Presentation, and Application layers with functions of each layer - scalable vector format

OSI 7-layer reference model
Figure 647.1: OSI 7-layer reference model for network communication

647.2 Learning Objectives

By the end of this section, you will be able to:

  • Understand Network Standards: Explain why standards and protocols enable global connectivity
  • Compare OSI and TCP/IP Models: Differentiate between the seven-layer OSI and four-layer TCP/IP models
  • Explain Encapsulation: Describe how data moves through protocol layers
  • Apply IoT Reference Models: Understand IoT-specific architectural frameworks
  • Configure MAC and IP Addressing: Work with hardware and network layer addresses
  • Implement IPv4/IPv6: Configure and troubleshoot both IP versions
  • Resolve Addresses: Understand ARP and how MAC/IP mapping works

647.3 Chapter Contents

This topic is covered in three focused chapters:

647.3.1 1. Layered Models Fundamentals

Core concepts of layered networking - Why standards matter, OSI 7-layer model, TCP/IP 4-layer model, protocol data units (PDUs), encapsulation/decapsulation processes, and IoT reference models.

Topics covered:

  • Networking standards and interoperability
  • OSI 7-layer model (theoretical framework)
  • TCP/IP 4-layer model (practical implementation)
  • Protocol data units at each layer
  • Encapsulation and decapsulation
  • IoT reference models (Cisco 7-Level, ITU)
  • Layer-by-layer troubleshooting

647.3.2 2. Addressing and Implementation

Hands-on addressing and configuration - MAC addressing, IPv4/IPv6 addressing, subnet masks, ARP protocol, and practical labs for configuring network addresses.

Topics covered:

  • MAC address structure and types
  • IPv4 addressing and subnet masks
  • IPv6 addressing and benefits for IoT
  • Address Resolution Protocol (ARP)
  • Hands-on configuration labs
  • Python implementation examples

647.3.3 3. Review and Knowledge Checks

Comprehensive review and assessment - Knowledge checks, quiz questions, worked examples, and visual reference galleries to reinforce understanding.

Topics covered:

  • Key concepts summary
  • Scenario-based knowledge checks
  • Protocol stack selection worked example
  • Visual reference gallery
  • Further learning resources

647.4 Quick Reference

TipMinimum Viable Understanding

The OSI model (7 layers) is a theoretical framework used for teaching and troubleshooting. The TCP/IP model (4 layers) is the practical implementation that powers the internet. Both use encapsulation - wrapping data in headers as it moves down the stack, and decapsulation - unwrapping headers as it moves up.

Key mapping: TCP/IP Application = OSI Layers 5-7, TCP/IP Transport = OSI Layer 4, TCP/IP Internet = OSI Layer 3, TCP/IP Network Access = OSI Layers 1-2.

Layer Type Addressing Scope
Data Link (L2) MAC addresses (48-bit) Local network segment
Network (L3) IP addresses (IPv4: 32-bit, IPv6: 128-bit) End-to-end routing

647.5 Prerequisites

Before diving into this section, you should be familiar with:

647.6 What’s Next

After completing these chapters, continue with: