QoS Support in MPLS Networks

MPLS is sometimes used synonymously with QoS, but more accurately, it is a QoSenabling technology that forces application flows into connection-oriented paths and provides mechanisms for traffic engineering and bandwidth guarantees along these paths. Furthermore, when an MPLS network supports DiffServ, traffic flows can receive classbased admission, differentiated queue servicing in the network nodes, preemption priority, and other network treatment that provide bases for QoS guarantees. The IETF work in this area has been augmented by the MPLS/Frame Relay Alliance Implementation Agreement which extends MPLS to the user-network interface, and thus serves as a foundation for implementing QoS end-to-end. This paper describes various QoS and MPLS mechanisms and analyzes their applicability.