NeTS: Small: Towards Exposing and Mitigating End-to-End TCP Performance and Fairness Issues in Data Center Networks

NetS：小型：致力于暴露和缓解数据中心网络中的端到端 TCP 性能和公平性问题

• 批准号: 1219004
• 负责人: Dongyan Xu
• 金额: $ 30万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1219004&HistoricalAwards=false
• 关键词: NeTS; Small; Towards; Exposing; Mitigating

While TCP was designed to work in any environment, it has a long history of problems whenever introduced in newer environments (e.g., wireless networks, satellite networks, high-capacity networks) that it was not explicitly designed and tested for. A similar new frontier that challenges TCP is the data center and cloud environments that have become popular in recent times. This project will conduct research on exposing end-to-end challenges that TCP faces in the modern cloud computing and data center environments and propose solutions to address them. Specifically, it focuses on three major issues surrounding TCP in data center and cloud environments: First, in virtualized cloud environments, when multiple VMs share the CPU, CPU access latency for each VM (i.e., the interval during which a VM waits for the CPU) is in the order of tens/hundreds of milliseconds and can be orders of magnitude higher than the typical sub-millisecond network RTTs. This high RTT causes significant reduction in TCP throughput. Second, in multirooted data center networks, under certain conditions, TCP connections sharing a common link exhibit severe unfairness. Finally, in data center networks today, equal-cost multipath routing (ECMP) is often used to split traffic across multiple paths, but it can potentially cause significant load imbalance. Researchers have refrained from suggesting packet-level multipath routing in the past because of its ability to cause reordering that may reduce TCP throughput. It is however not clear whether this poor interactions with multipath routing exists even under symmetric topologies such as fattrees, or more generally, multi-rooted tree topologies. Intellectual Merit: The goal of this project is to comprehensively investigate these afore-mentioned three major issues discussed above, propose new solutions to address the problems, and finally, validate these solutions and hypotheses using real prototype implementations and through extensive evaluations. (1) To address TCP's performance deterioration in virtualized cloud environments, the project will explore a new approach called transport function delegation, where certain TCP functions are delegated to the driver domain or hypervisor. (2) It will conduct extensive experimentation using real testbeds to expose, and characterize the unfairness issue, and also propose and evaluate classic solutions (e.g., RED) and a new routing algorithm called equal-length routing to mitigate this problem. (3) It will revisit the conventional wisdom that fine-grained multi-path traffic splitting protocols interact poorly with TCP, in the context of data center networks which have regular topologies such as multi-rooted trees. Broader Impact: The broader impact of this research comprises of the following: (1) It will help improve the key aspects of TCP such as performance and fairness in data center and cloud environments, that will benefit all data center systems and applications. (2) Results of this research will be transferred to industry. (3) Results of this research will be integrated into courses such as operating systems, computer networks, and cloud computing. It will also provide training to graduate students and several Ph.D. theses are expected to come out of this research. (4) It will include participation of minorities (under-represented minorities and women).

虽然TCP被设计为在任何环境中工作，但它在较新的环境中引入时都有很长的问题历史（例如，无线网络、卫星网络、高容量网络），这是它没有明确设计和测试的。 挑战TCP的一个类似的新领域是最近流行的数据中心和云环境。 该项目将研究TCP在现代云计算和数据中心环境中面临的端到端挑战，并提出解决方案。 具体来说，它主要关注数据中心和云环境中围绕TCP的三个主要问题：首先，在虚拟化云环境中，当多个VM共享CPU时，每个VM的CPU访问延迟（即，VM等待CPU的时间间隔）为几十/几百毫秒的量级，并且可以是比典型的亚毫秒网络RTT高的数量级。 这种高RTT导致TCP吞吐量显著降低。 第二，在多根数据中心网络中，在一定条件下，共享公共链路的TCP连接表现出严重的不公平性。 最后，在当今的数据中心网络中，等价多路径路由（ECMP）通常用于将流量拆分到多条路径上，但它可能会导致严重的负载不平衡。 研究人员在过去一直没有建议使用数据包级多路径路由，因为它能够导致重新排序，从而降低TCP吞吐量。然而，不清楚这种与多路径路由的不良交互是否存在于对称拓扑（如胖树或更一般的多根树拓扑）下。智力优势：本项目的目标是全面调查上述三个主要问题，提出新的解决方案来解决问题，最后，验证这些解决方案和假设使用真实的原型实现，并通过广泛的评估。 (1)为了解决TCP在虚拟化云环境中的性能恶化问题，该项目将探索一种称为传输功能委托的新方法，其中某些TCP功能被委托给驱动程序域或管理程序。 (2)它将使用真实的测试平台进行广泛的实验，以揭示和描述不公平问题，并提出和评估经典解决方案（例如，RED）和一种称为等长路由的新路由算法来缓解这个问题。(3)它将重新审视传统的智慧，细粒度的多路径流量分割协议与TCP交互不佳，在数据中心网络的背景下，具有规则的拓扑结构，如多根树。更广泛的影响：这项研究的更广泛影响包括：（1）它将有助于改善TCP的关键方面，例如数据中心和云环境中的性能和公平性，这将有利于所有数据中心系统和应用程序。 (2)这项研究的成果将转移到工业界。(3)这项研究的结果将被整合到课程，如操作系统，计算机网络和云计算。它还将为研究生和一些博士生提供培训。希望通过这项研究能有一定的成果。(4)它将包括少数群体的参与（代表性不足的少数群体和妇女）。