14.1 Introduction

Networks need addresses to identify objects and locations in the network. The structure of the address is the single largest influence on the nature of the network. To fully understand a network you must understand its address structure. This chapter describes in technical depth the structure of Internet protocol (IP) addresses and how these addresses are managed.

IP addresses are the unique numbers used to identify individual connections to the Internet; they are also a limited resource and the careful management of these IP addresses is essential to the running of the Internet. BT must be able to efficiently manage its own and its customers' IP addresses and it must be able to demonstrate good management of IP addresses in order to qualify for more IP address space. Without more new IP addresses BT would not be able to expand its IP network or launch new IP services. It is therefore of central importance to BT that it manages its IP addresses well.

The chapter starts with a description of what IP addresses are, before going on to outline the global IP address environment and how the global address space is managed through regional registries and organisations, such as Internet service providers (ISPs), for distribution to end users. This is followed by an examination of the process for obtaining addresses for an end user which highlights some of the rules which have to be followed by the ISP as part of this...