Introduction

Around 1981, the Internet Protocol Version 4 (IPv4) was standardized, one of the enablers behind the Internet and much of modern data communications. ISO/OSI layer 3 is the network layer, the layer which allows us to exchange packets between different networks.

Internet Protocol is all about having many interconnected networks (which are groups of addresses) in many locations. Everyone in the world knows where each block of addresses is, so a packet can get from any computer in the world to any other computer.

When the standard was developed, it was felt that 32 bits would be adequate for any address of any computer in the world. Unfortunately, that has not turned out to be the case. Our method for allocating address blocks was wasteful and we have more devices now than anyone ever anticipated. 32 bits for addresses would give us a potential 23^2 or 4,294,967,296 possible nodes. In these notes, we will look at addressing for IPv4.