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ACADEMIC YEAR	2000
NAME	CHO, Kenjiro
TITLE	The Design and Implementation of the ALTQ Traffic Management System
ABSTRACT	Traffic management to provide QoS (Quality-of-Service) is of great importance to the Internet. A large number of QoS mechanisms have been studied and proposed to date but such mechanisms are not widely used in today's Internet. The main reason is lack of a common QoS platform that can be used for both research and operation. In this dissertation, we present the design and implementation of the ALTQ traffic management system, a QoS platform based on the BSD UNIX operating system. The ALTQ system consists of a system framework that abstracts QoS functions, forwarding mechanisms that realize actual QoS, and management mechanisms that control the forwarding mechanisms. The system framework interfaces QoS mechanisms into the existing operating system. We find problems in the current output queue abstraction, and propose a new abstraction of output queueing that enables various types of service differentiation. We present required modifications to the operating system and propose incremental transition to the new model. The forwarding mechanisms provide a variety of QoS components to realize service differentiation. Low overhead is essential to the forwarding mechanisms since QoS components are placed on the packet forwarding path. We examine the theory, design and implementation of each QoS components available in the ALTQ system. The management mechanisms control the forwarding mechanisms. The QoS management mechanisms include a QoS agent, a QoS management library, and a QoS monitoring system. The ALTQ system is a flexible QoS platform that achieves low overhead and high performance in managing traffic. One can easily customize part of the ALTQ components and benefit from facilities provided by the other part of ALTQ. To this end, our focus is not only on designing a framework but also on engineering the system as a QoS platform for further reseach and experiements. In fact, ALTQ has been used worldwide for various research, experiments and production networks.
CONTACT	To obtain the whole paper, please contact; URL: http://www.csl.sony.co .jp/~kjc/papers.html E-Mail: kjc@csl.sony.co.jp

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