Rate-Based Flow Control Algorithms for High Speed Networks

在本计画中，我们将发展一个新的控制理论架构来设计高速网路中以速率为基础的强健流量控制器，而从这个架构所衍生出的演算法将适用于在ATM网路与网际网路中的实作。为此目的，PI将合作研究其专业领域中出现的具体问题：ATM和Internet流量控制，以及无穷维系统的鲁棒控制。 对于这类系统，将通过研究几种不同的方法，从H-无穷大控制，μ-综合，线性参数变化系统的增益调度，和李雅普诺夫稳定性理论，开发的随机设计方法。 特别地，将现有的有限维线性参数变化系统的增益调度技术推广到时滞系统，并通过与现有的ATM业务管理控制器的比较来验证在此框架下得到的控制器的有效性。新的流量控制器也将实施和实验测试。首先，它们将被翻译成算法，在现有标准的范围内在网络层（交换机和路由器）实现。 面向连接的网络（例如ATM网络）和无连接的网络（例如基于IP的Internet）都将在该项目中考虑。 在互联网领域，所使用的技术将包括写入TCP窗口，降低应答率，写入IP层的ECN位，以及在多协议标签交换（MPLS）体系结构中开发反馈框架。 为了实现这一目标，将开发新的技术来将基于速率的控制解决方案转化为基于窗口的控制解决方案（特别是在互联网流量管理中的适用性）。算法设计之后将进行性能评估，使用仿真和实验来评估这些方法对提供给网络多媒体应用的尽力而为服务的影响。实验技术将用于确定流量模型，和应用质量的网络措施，这将用于这些算法在代表性的网络配置的模拟研究。

In this project a new control-theoretic framework will be developed forrate-based robust flow controller design for high-speed networks, and thealgorithms derived from this framework will be adapted for implementation inATM networks and in the Internet. For this purpose the PIs will collaborateto investigate specific issues arising in their areas of expertise: ATM andInternet flow control, and robust control of infinite dimensional systems.The mathematical models to be considered in this project are systems withtime-varying time-delays. For this class of systems, controller-designmethods will be developed by investigating several different approaches fromH-infinity control, Mu-synthesis, gain scheduling for linear parametervarying systems, and Lyapunov stability theory. In particular, existinggain scheduling techniques for finite dimensional linear parameter varyingsystems will be extended to time delay systems.Controllers derived in this framework will be validated by comparing themwith the existing controllers designed for ATM traffic management. New flowcontrollers will also be implemented and tested experimentally. First theywill be translated into algorithms to be implemented at the network-layer(switches and routers) within the scope of existing standards. Bothconnection-oriented networks (e.g. ATM networks) and connectionless networks(e.g. IP based Internet) will be considered in the project. In the Internetdomain, techniques used will include writing into TCP windows, controllingthe rate of acknowledgements, writing into the ECN bit in the IP layer, anddeveloping a feedback framework in the Multi-protocol Label Switching (MPLS)architecture. Towards this goal, new techniques will be developed totranslate rate-based control solutions into window-based control solutions(especially for applicability in Internet traffic management).The algorithm design will be followed by a performance evaluation usingsimulation and experimentation to assess the impact of these methods onbest-effort services offered to networked multimedia applications.Experimental techniques will be used to determine traffic models, andnetwork measures of application quality, which will be used in simulationstudies of these algorithms in representative network configurations.