Tutorial Abstract: Overview of QoS for Packet-based IP and MPLS Networks

Paresh Shah, Utpal Mukhopadhyaya, Arun Sathiamurthi, Cisco
Level: Introductory

With the increased convergence of multi-services at the edge of the provider network, there is a greater need for effective bandwidth management and service differentiation essentially achieved through IP Quality of Service. In order to provide end-to-end scalable IP services, MPLS backbones are being used to achieve this. This has led to a wider deployment of MPLS-based backbones, enabling providers to have the capability to extend service differentiation using MPLS Diffserv techniques. This ability to provide traffic categorization along with traffic engineering and bandwidth management techniques, available through MPLS Traffic Engineering (TE) and Diffserv-Aware Traffic Engineering (DS-TE), allows the service provider an array of choices for end-to-end implementation of Quality of Service.

The five key components of QoS include delay, jitter, latency, bandwidth and fairness. Any QoS deployment requires attention to these components. This would be achieved at the edge by initially classifying traffic streams appropriately, then metering them towards providing service-level guarantees and, if needed, marking the streams as per-policy definitions. Subsequently, for effective bandwidth management, congestion avoidance and management techniques need to be implemented for better utilization of the links and for improved distribution of the available resources.

QoS in the MPLS core achieves differentiation using the MPLS EXP (experimental bit) and leverages the above-mentioned techniques. Additionally, there are benefits of providing congestion avoidance in the core by combining MPLS EXP-based classification with path selection and link and node protection schemes enabled by MPLS TE /FRR/ DS-TE.

This tutorial will begin by providing a background to the classical QoS techniques available for packet-based IP and MPLS networks. Subsequently it will introduce the concepts of MPLS Diffserv and briefly discuss the mapping between IP Diffserv and MPLS Diffserv at the edge. It will also briefly touch upon the concepts of MPLS QoS in conjunction with the path selection schemes through MPLS TE/FRR and DS-TE.

The following topics will be covered as part of this tutorial:

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