The evolution in networking technologies in the recent years has been driven by the development of such new multimedia applications as voice, video, graphics etc. If the Internet is to keep pace with the requirements of these applications, it is clear that Internet Service Providers must not only provide higher link capacities but also deploy more sophisticated service architectures. Another crucial task for building an Internet is the selection of a QoS-capable link layer. Asynchronous Transfer Mode could be the right support for the future Internet as it can deliver QoS to IP layer and has very high throughput. This book addresses some approaches to facilitate QoS guarantees in the Internet and to provide a flexible and scaleable environment for IP packets with differentiated QoS requirements over an ATM-based MPLS environment.