Collaborative Research: NeTS-NBD: Network X-ities - Foundations and Applications

从早期的ARPAnet到今天的全球互联网，大多数关于网络协议的研究都集中在传统的性能指标上，如延迟、丢失和吞吐量。然而，网络不仅要提供良好的性能，而且要面对复杂、不确定、容易出错和不断变化的环境，这一点变得越来越重要。在今天的网络中，操作条件可能会由于用户行为（例如，流量转移到一个新流行的网站）或底层基础设施（例如，设备故障）而发生变化。在所有这些情况下，网络及其运营商必须以稳健的方式做出响应，在不断变化的条件下继续提供良好的性能。对“健壮”网络操作的需求导致了一组设计考虑，主要研究人员（pi）将其称为“x - ity”（因为它们都以“ity”结尾）：非脆弱性、可管理性、可诊断性、可优化性、可伸缩性和可演化性。直觉上，我们知道，如果我们要设计和分析健壮的网络和协议，这些x是至关重要的。然而，与标准性能指标相比，这些指标往往缺乏理论基础、定量框架，甚至缺乏定义良好的指标和意义。该项目的目标是为明确考虑网络协议设计和分析中的x点建立一个严格的、定量的基础。pi考虑了一些具体的问题，广泛地在路由协议领域，具体地解决了几个x - ity（特别强调非脆弱性和可管理性），并开始从所研究问题的共性中吸取更大的教训。建议的研究重点是在路由协议的背景下的x点，以确保每台计算机都有通过网络向其他计算机发送数据的路径。这种选择有几个原因。首先，路由协议是网络体系结构的关键部分——它们是将互联网的不同部分粘合在一起的粘合剂。其次，IP路由的x点还没有得到正式的重视。第三，路由协议暴露了信息不完整（例如，跨由不同机构运行的网络）和控制交互级别（例如，应用程序和底层网络之间）的关键问题——这些问题应该在任何彻底处理网络x的过程中出现。最后，路由提供了一个引人注目的上下文，在这个上下文中可以定量地研究x线。例如，我们可以量化针对狭窄的、定义良好的操作条件进行优化的脆弱路由解决方案与在多种操作条件下性能良好的解决方案之间的性能权衡。提出的研究的贡献有三个方面：第一次对x的定量研究：严格理解x的智力挑战很多。pi定义特定的度量标准并开发数学模型来定量研究每个x - city。具体问题的解决方案：为了使x - ity的研究具体化，pi在路由领域广泛地考虑一组研究问题，这些问题对他们自己的权利感兴趣。建立研究x点的基础：pi认为，网络x点的研究是网络长期研究的一个至关重要的领域。x - city的研究将导致对如何开发强大的网络架构和协议的更深入的定量理解，这些技术在我们的日常生活中发挥着越来越重要的作用。这项研究的更广泛影响将包括加强我们学生的教学、培训和学习，开发和传播新的教育材料，以及在整个技术社区传播x - city的研究成果。

0519880 0519998From the early days of the ARPAnet to today's global Internet, most research on network protocols has focused on traditional performance metrics such as delay, loss, and throughput. However, it is becoming increasingly important that a network not only provides good performance, but also do so in the face of a complex, uncertain, error-prone, and ever-changing environment. In today's networks, operating conditions may change as a result of user behavior (e.g., a shift in traffic to a newly popular Web site) or the underlying infrastructure (e.g., an equipment failure). In all such cases, the network and its operators must respond in a robust fashion, continuing to provide good performance despite changing conditions.The need for "robust" network operation leads to a set of design considerations that the principal investigators (PIs) refer to as the "X-ities" (since they all end in "ity"): non-fragility, manageability, diagnosability, optimizability, scalability, and evolvability. Intuitively, we know that these X-ities are crucially important if we are to design and analyze robust networks and protocols. Yet, compared with standard performance metrics, these X-ities often lack theoretical foundations, quantitative frameworks, or even well-defined metrics and meaning. The goal of this project is to build a rigorous, quantitative foundation for explicitly considering the X-ities in the design and analysis of network protocols. The PIs consider a number of specific problems, broadly in the area of routing protocols, that concretely address several of the X-ities---with particular emphasis on non-fragility and manageability---and to begin to draw larger lessons from commonalities among the problems studied.The proposed research focuses on the X-ities in the context of the routing protocols that ensure that each computer has paths through the network to send data to other computers. There are several reasons for this choice. First, routing protocols are a crucial part of the network architecture---they are the very glue that holds the disparate parts of the Internet together. Second, the X-ities of IP routing have not received significant formal attention. Third, routing protocols expose key issues of incomplete information (e.g., across networks run by different institutions) and interacting levels of control (e.g., between applications and the underlying network)---concerns that should arise in any thorough treatment of network X-ities. Finally, routing provides a compelling context in which the X-ities can be quantitatively studied. For example, we can quantify the performance trade-off between a fragile routing solution that has been optimized for narrow, well-defined operating conditions, versus a solution that will perform well of over variety of operating conditions. The contributions of the proposed research are three-fold: A first quantitative study of X-ities: The intellectual challenges in rigorously understanding the X-ities are many. The PIs define specific metrics and develop mathematical models to quantitatively study each X-ity. Solutions to specific problems: To make the study of the X-ities concrete, the PIs consider a set of research problems broadly in the area of routing that are of interest in their own right. The beginnings of a foundation for studying X-ities: The PIs believe that the study of network X-ities is a crucially important area for long-term research in networking. The X-ity research will lead to a deeper quantitative understanding of how to develop robust network architectures and protocols---technology that is playing an increasingly crucial role in our daily lives. The broader impacts of the research will include enhanced teaching, training, and learning for our students, development and dissemination of new educational materials, and dissemination of X-ity research results throughout the technical community.