NeTS-NR: Counter-Intuitive Behavior in General Networks

提案编号：0435520PI: Steven LowInstitution: California Institute of Technology标题：通用网络中的反直觉行为摘要众所周知，反直觉行为可能出现在分布式系统中，其中代理优化自己的目标。本项目研究TCP网络中复杂的交互。重点是具有多链路和异构流的一般网络拓扑结构以及严格的数学建模和分析。该项目发展数学理论来理解大规模网络的行为，在模拟和真实网络中验证这些理论见解，并在网络和协议的实际设计和操作中加以利用。初步结果表明，有趣和反直觉的行为只会出现在网络环境中，其中流通过多个共享链接以令人惊讶的方式相互作用。例如，研究人员已经证明，增加链路容量可以降低TCP网络中的总吞吐量，而且，与传统观点相反，公平的带宽分配并不一定是低效的。这些结果表明，项目中采用的正式方法确实是必要的和有益的。这个项目的结果将帮助我们更好地理解像互联网这样的大型网络的行为，特别是，有助于描述矛盾现象，并得出避免TCP网络中有害行为的指导方针。PI与普林斯顿大学电子工程学院的Chiang Mung教授合作，正在开发一门关于“通信网络的控制和优化”的新课程，用于研究生和高级本科生的入门课程。项目成果将直接纳入新课程。我们还将利用并促进这一倡议的教育和外联活动。

Proposal Number: 0435520PI: Steven LowInstitution: California Institute of Technology Title: Counter-Intuitive Behavior in General Networks Abstract It is well-known that counter-intuitive behavior can arise in a distributed system where agents optimize their own objectives.This project studies the intricate interactions in TCP networks. The emphasis is on general network topologies with multiple links and heterogeneous flows and on rigorous mathematical modeling and analysis. The project develops mathematical theory to understand the behavior of large scale networks, verifies these theoretical insights in simulations and real networks, and exploits them in practical design and operation of networks and protocols.Preliminary results illustrate that interesting and counter-intuitive behavior arises only in a network setting where flows interact through multiple shared links in surprising ways. For example, the researchers have shown that increasing link capacity can reduce the aggregate throughput in a TCP network, and that, contrary to conventional wisdom, a fair bandwidth allocation is not necessarily inefficient. These results demonstrate that the formal approach taken in the project is indeed necessary and rewarding.The results of this project will help us better understand behavior of large-scale networks such as the Internet, and in particular, help characterize paradoxical phenomenon and derive guidelines to avoid harmful behavior in TCP networks.Together with Professor Mung Chiang of Princeton EE, the PI is developing a new course on ``Control and optimization of communication networks'', at the introductory graduate andadvanced undergraduate level. The results produced in the project will be directly incorporated into the new course. We will also leverage on, and contribute to, the education and outreach activities of this initiative.