728  Transport Protocols: Fundamentals

728.1 Transport Layer Protocols for IoT

The transport layer (Layer 4) provides end-to-end communication between IoT applications. This guide covers TCP, UDP, and DTLS - the three protocols that form the backbone of IoT networking. Understanding when to use each protocol is critical for balancing reliability, latency, and power consumption in your IoT deployments.

NoteLearning Objectives

By completing all five chapters, you will be able to:

  • Understand the role of transport layer protocols in IoT
  • Compare TCP and UDP characteristics and use cases
  • Explain why UDP is preferred for many IoT applications
  • Understand DTLS (Datagram Transport Layer Security) for securing UDP
  • Analyze trade-offs between reliability, overhead, and power consumption
  • Select appropriate transport protocol for different IoT scenarios
  • Implement reliable message transport systems
  • Avoid common pitfalls in transport protocol selection

728.2 Chapter Navigation

This guide is split into five focused chapters:

728.2.1 1. Transport Protocols Overview (~2,450 words)

Introduction to transport layer protocols, prerequisites, and beginner-friendly explanations of TCP vs UDP. Includes video resources, analogies, and the Sensor Squad story for kids.

728.2.2 2. User Datagram Protocol (UDP) (~1,700 words)

Deep dive into UDP characteristics, header structure, and IoT applications. Covers connectionless communication, checksum importance, and knowledge check quizzes.

728.2.3 3. Transmission Control Protocol (TCP) (~3,230 words)

Comprehensive TCP coverage including 3-way handshake, reliable delivery mechanisms, connection state management, and why TCP is essential for firmware updates.

728.2.4 4. TCP vs UDP: Comparison and Selection (~2,210 words)

Detailed feature comparison, engineering tradeoffs, and an interactive protocol selector tool. Includes decision frameworks for choosing between TCP and UDP.

728.2.5 5. Practical Applications and Labs (~7,910 words)

Real-world examples, common mistakes, worked examples with battery calculations, and a hands-on ESP32 lab for building a reliable message transport system.

728.3 Quick Reference

Protocol Header Connection Reliability Best For
UDP 8 bytes Connectionless Best-effort Sensor telemetry, streaming
TCP 20-60 bytes Connection-oriented Guaranteed Firmware, configuration
DTLS ~50 bytes Session-based Secured UDP Secure IoT telemetry

728.4 Prerequisites

Before starting, you should be familiar with:

728.6 What’s Next

Start your journey with Transport Protocols Overview or jump directly to the protocol deep dives: