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IP Sub-Networking Mini-Howto

Robert Hart, `hartr@interweft.com.au`

v1.1, 30 August 2001

This document describes why and how to subnetwork an IP network - that is using a single A, B or C Class network number to function correctly on several interconnected networks.

1. Copyright

2. Introduction

2.1 Other sources of information

3. The Anatomy of IP numbers

3.1 IP numbers belong to Interfaces - NOT hosts!
3.2 IP Numbers as "Dotted Quads"
3.3 Classes of IP Networks
3.4 Network numbers, interface addresses and broadcast addresses
3.5 The network mask

4. What are subnets?

5. Why subnetwork?

6. How to subnetwork a IP network number

6.1 Setting up the physical connectivity
6.2 Subnetwork sizing
6.3 Calculating the subnetwork mask and network numbers

7. Routing

7.1 The routing tables