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“Quality of Service Provisioning for Multimedia Applications in Service Differentiation Networks”
by Jitae Shin
May 2001
Internet applications have very diverse requirements on the network service such as the emerging continuous media (CM) applications demand more stringent quality of service (QoS) requirements than traditional TCP-based applications. Internet QoS remains as an efficient solution different application requirements even if the bandwidth will become abundant and cheap.
To provide some level of service reliability, the current best-effort Internet must be supplemented with the ability to differentiate traffics and to realize different service levels for different applications. The Differentiated Services (DiffServ) framework being defined by IETF intends to meet the need of providing differentiated classes for various types of applications with relatively simple and coarse methods. The imminent deployment of DiffServ networks will benefit a lot if multimedia applications at end-systems are aware of their service model.
We present a futuristic QoS mapping framework. First, we propose a video categorization scheme based on the concept of relative priority index (RPI) with the practical guidelines of effective QoS mapping between categorized application streams and network DiffServ levels under a total cost constraint. RPI plays a good bridging tool in enabling the network to be content-aware in order to achieve better end-to-end video quality. Second, we present an adaptive packet forwarding mechanism to provide more persistent network DiffServ levels regardless of the network load fluctuation. Third, a dynamic QoS mapping control scheme, including feedforward and feedback QoS control, is studied for DiffServ networks. To achieve reliable and consistent end-to-end CM streaming with relative service differentiation, we develop a dynamic and aggregate QoS mapping control scheme with packet, session, and class-based granularity levels for categorized packets at the CM gateway, which is located at the edge of the DiffServ domain. Finally, we propose a lightweight packet scheduling algorithm that allocates forwarding resources to different classes for absolute service differentiation in terms of delay/jitter and target rates, which is called the controlled priority (CP) gateway algorithm. The proposed algorithm can provide guaranteed bounds of delay, jitter, rate, and packet loss to certain aggregate flows without an adverse effect to total link utilization.