1.1 Introduction

This chapter describes what is meant by a carrier-scale IP network. It details the challenges in designing, building and operating a carrier-scale IP network, and lists the abilities required in a network to make it carrier-scale, e.g. scalable, manageable, performant and secure. Also described are the challenges for the future when developing an esoteric protocol or service, such as multicast or VoIP, into a carrier-scale protocol or service. None of the challenges highlighted here should be underestimated in their capability to confound, and they are best met by applying the solid design and operations principles covered in the following chapters.

Firstly, the term 'carrier-scale IP network' has to be defined before its properties and challenges can be described. A 'carrier-scale IP network' is an IP network with the following properties:

• it provides services for millions of end users;

• it provides high-speed, greater than 100 Mbit/s, transit services to other Internet service providers (ISPs) in a traditional retail/wholesale model this would be considered a wholesale service;

• it is reliable, scalable and manageable.

Today's best Internet providers demonstrate these features and tomorrow's IP virtual private networks (VPNs) will have these features.

Many challenges face the designers, engineers, builders and operators of large global IP networks. The challenges range from the physical challenges of finding enough accommodation with enough power and air-conditioning, to the more abstract challenge of configuring the network in such a way that it performs well and operates reliably. Configuring a network can be...