15.1 Introduction

Data traffic, particularly IP, continues to grow at an explosive pace. Leading Internet providers report bandwidths doubling on their backbones approximately every six to nine months. The Web-driven growth in demand for bandwidth of recent years will be followed by successive waves of demand attributable to voice over IP (VoIP), video, and high-speed subscriber access via digital subscriber lines (DSL) and cable. The adoption of intranets and extranets for networked commerce will bring further changes to the IP-service infrastructure, both through bandwidth demands and feature requirements.

Service providers recognise the unprecedented explosion of packet-based traffic and are re-evaluating their IP network architectures in the light of these changes. The traditional IP network, generally built as an overlay to a layer-2 technology such as frame relay or ATM, are being phased out in favour of simpler, more cost-effective models. These rely on the IP router connecting directly to dark fibre and/or dense 'wave division multiplexing' (WDM) equipment and effectively putting IP packets directly on to the glass. This scheme removes multiple layers of hierarchy and offers significantly more bandwidth, flexibility and cost savings but does offer some additional challenges.

One of the key challenges is how to utilise the network's resources to their best effect. In traditional IP networks, this was through a combination of the interior gateway protocol and the traffic engineering capabilities of the underlying layer-2 infrastructure. With the removal of the layer-2 infrastructure, this traffic engineering function needs to be performed elsewhere.

This chapter...