3 – Differentiated Services

Publisher Summary The Differentiated Services approach to supporting quality of service (QoS) capabilities in the Internet employs a small, well-defined set of building blocks from which a variety of aggregate behaviors can be built. It offers a simpler solution from the viewpoint of implementation and deployment. This chapter describes the main concepts and the overall architecture of Differentiated Services, and explains the key differences between Differentiated Services and Integrated Services. It discusses the traffic classification and conditioning functions at the edge of a Differentiated Services network. Traffic conditioners perform traffic-policing functions to enforce the traffic conditioning agreement (TCA) between customers and service providers. Differentiated Services focuses on resource management for a single domain, particularly backbone domains. Performance assurance in Differentiated Services networks is provided by a combination of resource provisioning, traffic prioritization, and admission control. It is important that the networks are carefully provisioned to avoid mismatch between traffic patterns and bottleneck bandwidth. Additional mechanisms may be needed to detect misbehaving and malicious traffic sources.