IP quality of service architectures

ISP are facing the challenge of offering improved quality of service (QoS). No longer is best effort delivery with no service guarantee acceptable for many applications. IP traffic requires a degree of engineering into service classes (Differentiated Services) as well as a break from traditional layer 3-based routing. Although access to virtually unlimited bandwidth via WDM and photonic networks may potentially offer a solution to the QoS issue, access to such services is not universally available. Label switching offers an efficient mechanism to implement IP traffic engineering, Differentiated Services, multi-service functionality and scalability. This paper examines a number of service classifications and solutions which aim to provide realistic QoS solutions. These include important traffic engineering methodologies such as Integrated and Differentiated Services, multi-layer switching, MPLS and constraint-based routing.