The QoSbox: quantitative service differentiation in BSD routers
Computer Networks: The International Journal of Computer and Telecommunications Networking
Enhancing class-based service architectures with adaptive rate allocation and dropping mechanisms
IEEE/ACM Transactions on Networking (TON)
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In this dissertation, we present a novel service architecture for the Internet, which reconciles application demand for strong service guarantees with the need for low computational overhead in network routers. The main contribution of this dissertation is the definition and realization of a new service, called Quantitative Assured Forwarding, which can offer absolute and relative differentiation of loss, service rates, and packet delays to classes of traffic. We devise and analyze mechanisms that implement the proposed service, and demonstrate the effectiveness of the approach through analysis, simulation and measurement experiments in a testbed network. To enable the new service, we introduce a set of new traffic control algorithms for network routers. The main mechanism proposed in this dissertation uses a novel technique that performs active buffer management (through dropping of traffic) and rate allocation (for scheduling) in a single step. This is different from prior work which views dropping and scheduling as orthogonal tasks. We propose several solutions for rate allocation and buffer management, through solutions to an optimization problem, approximations of such a solution, and through a closed-loop control theoretical approach. Measurement results from a testbed of PC-routers on an Ethernet network indicate that our proposed service architecture is suitable for networks with high data rates. We extend the service guarantees of Quantitative Assured Forwarding to TCP traffic by integrating our buffer management and rate allocation algorithms with the feedback capabilities of TCP, and regulate the sending rate of TCP traffic sources at the microflow level. The presented techniques show, for the first time, that it is feasible to give service guarantees to TCP traffic flows, without per-flow reservations in the network.