Traffic Control for Networks with Aggregate Quality-of-Service

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As the Internet continues to expand into new application domains, there is a growing demand for differentiated services that provide varying degrees of Quality of Service (QoS). Until recently, the approach for service differentiation in the Internet has focused on providing QoS guarantees to individual traffic flows. This per-flow model has not been widely embraced, largely due to the vast amount of state information that needs to be maintained in the network. As a consequence, the network community is currently redefining the notion of QoS for the Internet, leading to a new service model where guarantees are made to appropriate flows, rather than to individual flows.The notions of aggregate QoS which are being defined, e.g., by the Differentiated Services (DiffServ) working group in the IETF, are very different from traditional networking concepts and require novel algorithms for traffic control and provisioning. The objective of the proposed research is to give fundamental insights into the nature and delivery of QoS to traffic aggregates, henceforth called aggregate QoS.A central feature of service models for aggregate QoS is that there is no requirement for users to specify the composition or the destination of traffic. This significantly complicates the provisioning of network resources and suggests that new, feedback-intensive traffic control algorithms must be developed to mitigate uncertainty about network loading. At present there is little or no theory available to guide the development of such algorithms. The proposed research will remedy this situation by developing analytical tools that will make aggregate QoS possible for the next-generation Internet.The three main research components of this proposal involve development of analysis techniques and computational simulation experimentation.1. The projectl proposes to develop a novel fluid-flow, network-optimization model that will facilitate (a) rapid analysis of aggregate QoS networks and (b) improved routing, based on feedback about network traffic patterns.2. Using a new construct of so-called effective envelopes, the project will develop a method for computing the statistical multiplexing gain in a network with aggregate QoS. Knowledge of the statistical multiplexing gain is essential for determining the amount of traffic with aggregate QoS that can be supported in a network.3. The project will build a packet-level simulation environment, which will enable the development and testing of a wide variety of traffic control algorithms for aggregate QoS networks. This research will help to identify metrics for comparing the effect of traffic control algorithms to support aggregate QoS. An important part of our work is to determine the extent to which feedback-base traffic control can alleviate the provisioning problem.By providing a theoretical reference frame for aggregate QoS, which provides tools and techniques for capacity provisioning and admission control, the proposed research will complement the currently ongoing standardization efforts for differentiated services on the Internet.