End-to-end QoS implement by DiffServ and MPLS

All the new emerging QoS architectures are motivated by the desire to improve the overall performance of an IP network. While the integrated services (IntServ) architecture provides a means for the delivery of end-to-end QoS, it is not scalable or practical to operate and manage. Differentiated services (DiffServ) defines a model for implementing scalable differentiation of QoS in the Internet, but it has the drawback of providing no guarantees. Multiprotocol label switching (MPLS) is a fast label-based switching technique that offers new QoS capabilities for large scale IP networks. When an MPLS network supports DiffServ, traffic flows can receive class-based network treatment that provides bases for QoS guarantees, and these guarantees come with better scalability and reduced complexity in comparison with IntServ. We describe a service architecture model where part of the underlying technology used for IP transport is MPLS using DiffServ-like mechanisms and constraint based routing for traffic engineering.