Evaluation and Development of Traffic Control Methods for Very High Speed Communication Networks

在这个项目中，我们评估和开发了适用于高速网络，特别是专用于ATM网络的流量控制方法。我们首先讨论了语音、运动视频和文件传输等多种业务在网络中共存时，统计复用增益的影响。我们进一步讨论了在网络中处理不同服务质量的多媒体业务时优先级控制的有效性。然后，我们使用前向纠错(FEC)方法对高可靠数据传输协议进行了评估。这项研究表明，FEC可以作为一种未来的数据传输协议，以获得很低的信元丢失率。基于速率的拥塞控制被应用于未来基于ATM的互联网中的数据传输。我们的下一个贡献是发展了基于速率的拥塞控制的分析方法。通过数值算例，展示了其在ATM交换机上的实现方法，为有效而简单的流量控制提供了方法。在交换机上观察到的最大队列长度的分析结果可用于ATM交换机设计中的缓冲区大小。在未来的高速网络中，除了数据传输之外，还应该支持运动视频等实时业务。在这种情况下，媒体之间的同步机制变得非常重要。我们提出了三种同步机制，并在运行在基于Unix的工作站上的超媒体系统Harmony上实现了所有这些方法。虽然建议的机制在应用程序级别得到支持，但当系统用作演示系统时，它是有用的。

In this project, we evaluate and develop the traffic control methods suitable to high speed networks, especially dedicated to ATM networks. We first discuss on the effect of statistical multiplexing gain when the multiple traffic classes including voice, motion video and file transfer co-exist in the network. We further address the effectiveness of priority control when the multimedia traffic with different quality of service are handled in the network. Then, we evaluate the highly reliable data transport protocol using FEC (Forward Error Correction) method. By this study, it is demonstrated that FEC can be suitable as a future data transport protocol to attain the very low cell loss probabilities. The rate-based congestion control is applied to data transfer in the future ATM-based betworks. Our next contribution is that the analysis method for the rate-based congestion control is developed. Through the numerical examples, we show its implementation method of the ATM switch for effective and simple traffic control method. The analysis result for maximum queue length observed at the switch can be used for buffer dimensioning in designing the ATM switch. In the future high speed networks, the real time traffic such as motion video should also be supported in addition to the data transfer. In the case, the synchronization mechanisms among the media becomes important.We have poposed three synchronization mechanisms and implemented all of these methods on Harmony, which is our hyper-media system running on the UNIX-based workstation. While the proposed mechanisms are supported at the application level, it is useful when the system is used as the presentation system.