639 Networking: Addressing and Subnetting

639.1 Overview

This comprehensive guide to IP addressing and subnetting has been organized into focused chapters for easier learning. Each chapter covers a specific aspect of network addressing essential for IoT deployments.

MVU: Minimum Viable Understanding

Core concept: Every device on a network needs a unique IP address, and subnets divide large networks into manageable segments using masks that separate the “network” from “host” portions of addresses.

Why it matters: Incorrect IP addressing causes silent failures - devices simply cannot communicate, with no helpful error messages to diagnose the problem.

Key takeaway: Use private IP ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x) for internal IoT networks, and plan /24 subnets (254 hosts) per floor, building, or sensor type.

639.2 Chapter Guide

Select the chapter that matches your learning goals:

639.2.1 IPv4 Addressing Fundamentals

Topics: 32-bit address structure, binary conversion, address classes (historical), private IP ranges (RFC 1918), special-purpose addresses, MAC address OUI

Best for: Understanding the building blocks of IP addressing

639.2.2 Subnetting and CIDR

Topics: Subnet masks, network/host division, CIDR notation, calculating network and broadcast addresses, VLSM, IoT subnet design patterns

Best for: Learning to divide networks and plan efficient address allocation

639.2.3 Port Numbers and NAT

Topics: Port number ranges (well-known, registered, ephemeral), IoT protocol ports (MQTT, CoAP, HTTP), 5-tuple connections, NAT translation, NAT traversal patterns for IoT

Best for: Understanding service identification and internet connectivity for IoT

639.2.4 IPv6 for IoT

Topics: 128-bit addresses, compression rules, address types (global, link-local, unique-local), 6LoWPAN header compression, SLAAC, IPv4/IPv6 transition strategies

Best for: Preparing for next-generation IoT networks and Thread/Matter protocols

639.2.5 DHCP and Address Resolution

Topics: DHCP DORA process, lease management, DHCP options, DHCP reservations, ARP for IPv4, Neighbor Discovery for IPv6, troubleshooting IP conflicts

Best for: Configuring automatic IP assignment and understanding address resolution

639.3 Learning Objectives (Complete Guide)

By completing all chapters, you will be able to:

Assign IP Addresses: Configure IPv4 and IPv6 addresses for IoT devices and networks
Design Subnets: Calculate subnet masks and plan network segmentation for IoT deployments
Configure Port Numbers: Identify and use standard ports for IoT protocols (MQTT, CoAP, HTTP)
Implement NAT and DHCP: Set up address translation and automatic IP assignment for device networks
Plan Private Networks: Design internal networks using RFC 1918 private address ranges
Troubleshoot Addressing Issues: Diagnose IP conflicts, routing problems, and connectivity failures

639.4 Prerequisites

Before diving into these chapters, you should be familiar with:

Networking Basics: Foundation in networking concepts, IP addressing fundamentals, and protocol basics
Network Mechanisms: Understanding how datagrams, packet switching, and network communication work
Layered Network Models: Knowledge of where addressing operates within the OSI/TCP-IP models (primarily Layer 3 - Network Layer)

639.5 Quick Reference

639.5.1 Private IP Ranges (RFC 1918)

Range	CIDR	Addresses	Typical Use
10.0.0.0 - 10.255.255.255	/8	16.7 million	Large enterprise, smart cities
172.16.0.0 - 172.31.255.255	/12	1 million	Medium industrial networks
192.168.0.0 - 192.168.255.255	/16	65,536	Home automation, small buildings

639.5.2 Common IoT Ports

Protocol	Port	Transport	Use Case
MQTT	1883	TCP	Lightweight messaging
MQTT/TLS	8883	TCP	Secure MQTT
CoAP	5683	UDP	Constrained devices
HTTP	80	TCP	Web interfaces
HTTPS	443	TCP	Secure web/APIs

639.5.3 Subnet Quick Reference

CIDR	Usable Hosts	Use Case
/30	2	Point-to-point links
/28	14	Small room automation
/27	30	Single floor
/26	62	Medium building floor
/24	254	Standard building network
/22	1,022	Large campus