NeTS: Large: Collaborative Research: Complex Interactions in the Content Distribution Ecosystem

网络搜索（如b谷歌和必应）、社交网络（如Facebook）和在线视频流（如Netflix和YouTube）等互联网服务现在是一项重要的人类活动。这些服务的基础是一个庞大且日益复杂的服务器、网络和软件系统，由各种实体控制，如拥有或生成内容的内容提供商（CPs）、将内容分发给用户的内容分发网络（cdn）和拥有并运营底层网络基础设施的互联网服务提供商（isp）。这些实体形成了内容分发生态系统，每个实体都有自己的商业利益，每个实体都试图优化自己的成本和性能，通常是单独的，但有时也会与其他实体合作。这个项目的重点是理解这些不同实体之间的复杂交互，以提供更好的体系结构解决方案来促进这些交互。从该项目中获得的见解可以帮助指导未来互联网服务的发展，从而为用户提供更好的体验质量（QoE），并为生态系统中的实体提供更高的系统效率。该项目提出了一个框架，从多个角度研究内容分发生态系统中的复杂交互——控制信息、决策点、时间尺度和本地与全球决策，并应用该框架来理解它们对用户QoE的作用和影响。该项目沿着四个主线组织：1)CDN和ISP之间的复杂交互：表征CDN行为（如内容适应和请求路由）对ISP行为（如流量工程和流量整形）的影响；2) CPs和CDN之间的复杂交互：用CDN行为（如服务器选择）来描述CP行为（如选择正确的CDN来传递其内容）；3)（单路径和多路径）TCP和应用程序之间的复杂交互：描述视频流等应用程序和（MP）TCP等协议中存在的控制回路之间的交互；4)测量，跟踪驱动的评估，以及控制和“野外”实验。所有这四个线程都是通过分析的推力连接起来的，重点是理论模型的发展，先进的算法，以及基于优化，控制和经济方法的性能界限。这个项目背后的主要前提是，随着实体数量的增加和它们之间各种交互的增加，内容分发变得越来越复杂。这种复杂性需要新的分析和算法方法来建模、理解、控制和优化内容分发。该项目朝着开发这些工具和方法迈出了第一步，并将它们应用于cp、cdn和isp之间以及不同应用程序级和传输级数据传输之间的交互。项目如获成功，可为有效改善系统性能及提升整体用户质素提供完善的理论基础及一般设计指引，并令cp、cdn及isp均受惠。这个项目的成功完成有望提高内容分发生态系统和整个互联网基础设施的经济可行性。此外，它将使我们更好地理解如何设计由许多不同的相互作用的组件组成的大型系统。本计画的教育活动将加强网络、建模、控制理论和复杂系统交叉领域的本科、研究生和专业教育。pi将通过以下方式实现这些目标：1)创建适合高年级学生和研究生的复杂系统、内容分发系统和交互系统数学的课程和课程材料；2)开展外联活动，旨在增加本科女性和少数民族学生参与研究以及与更广泛的网络社区的接触。

Internet services such as web search (e.g, Google and Bing), social networks (e.g., Facebook), and online video streaming (e.g., Netflix and YouTube) are now an important human activity. Underlying such services is a vast, and increasingly complex system of servers, networks, and software controlled by a variety of entities such as content providers (CPs) who own or generate the content, content distribution networks (CDNs) who distribute that content to users, and Internet Service Providers (ISPs) who own and operate the underlying network infrastructure. These entities form the content distribution ecosystem, each with its own business interest, each attempting to optimize its own cost and performance, more often individually, but sometimes in cooperation with others. This project is focused on understanding the complex interactions among these different entities with the view of providing better architectural solutions to facilitate those interactions. Insights gained from the project can help guide the evolution of future Internet services, resulting in better quality-of-experience (QoE) for the users and greater system efficiencies for the entities in the ecosystem. This project advances a framework to study complex interactions in the content distribution ecosystem from multiple perspectives -- control information, decision points, time scales and local vs. global decision making, and applies this framework to understand their roles and effects on user QoE. The project is organized along four main threads: 1) Complex interactions between CDNs and ISPs: Characterize effects of CDN actions such as content adaptation and request routing on ISP actions such as traffic engineering and traffic shaping; 2) Complex interactions between CPs and CDNs: Characterize CP actions such as choosing the right CDN to deliver their content with CDN actions such as server selection; 3) Complex interactions between (uni- and multi-path) TCP and applications: Characterize interactions between control loops present in applications such as video streaming and protocols such as (MP)TCP; 4) Measurement, trace-driven evaluation, and controlled and "in the wild" experimentation. All four threads are connected by an analytical thrust focused on the development of theoretical models, advanced algorithms, and performance bounds based on optimization, control and economic methods.The main premise behind this project is that content distribution is becoming more complex with increasing numbers of entities and varied interactions between them. This complexity requires new analytical and algorithmic methods to model, understand, control, and optimize content distribution. The project takes a first step towards developing these tools and methods, and applying them to interactions that arise between CPs, CDNs, and ISPs, and between different application-level and transport level data transfers. If successful, the project will produce sound theoretical underpinnings and provide general design guidelines in effectively improving the system performance and enhancing overall user QoE and benefit CPs, CDNs and ISPs alike.The successful completion of this project promises to enhance the economic viability of the content distribution ecosystem and the Internet infrastructure at large. Moreover, it will lead to a better understanding of how to engineer large systems consisting of a multitude of diverse interacting components. Educational activities for this project will enhance undergraduate, graduate, and professional education lying at the intersection of networking, modeling, control theory, and complex systems. The PIs will accomplish these goals through 1) creation of courses and course material on complex systems, content distribution systems, and mathematics of interacting systems appropriate for seniors and graduate students; 2) development of outreach activities aimed at increasing participation of undergraduate women and minority students in research as well as engagement with the broader networking community.