STI: Effective Diagnostic Strategies for Wide Area Networks

端到端网络性能难题中的一个关键缺失部分源于当前的网络诊断策略没有充分考虑路径延迟的影响。这是一项建议，旨在开发对现有诊断工具的扩展，这些工具将有效地考虑路径延迟，补偿各种延迟时间，并使用实际高性能应用程序向网络用户和运营商测试这些新诊断工具的效果。端到端互联网诊断是一个如此困难的问题，因为几乎所有缺陷的症状都会随着路径延迟而扩大，而随着延迟而扩大的症状会导致传统的诊断策略产生误导性的结果。传统的诊断工具和策略产生令人困惑的结果，因为仅仅改变路径延迟就会改变缺陷的症状，即使缺陷不在路径的附加部分。这种新的诊断方法使用几种不同的技术来补偿路径延迟对诊断结果的影响：模拟延迟，它使用专门的软件来缓冲和延迟分组，就像它们穿过长路径一样；参数模型缩放，一种通过验证短路径是否实现了TCP满足端到端性能目标所需的属性来验证短路径是否可以支持长路径上的TCP批量传输的方法；以及“风景”虚拟专用网络，其中可以通过使用各种IP隧道或虚拟专用网络在长的“场景”备用路由上发送分组来延迟分组。这些技术将与现有的诊断工具和战略结合使用。该项目将开发一套增强的诊断工具，以补偿路径延迟的影响。该套件将面向几种不同的受众：真正的最终用户、应用程序开发人员、网络管理员和诊断专家或工具开发人员。该套件将由一小部分核心组件构建而成，这些组件实现了前面描述的补偿路径延迟的技术，并结合一些简单的诊断应用程序。将部署一个由诊断服务器和放置在网络中的测试目标组成的原型诊断基础设施。原型诊断基础设施将部署在匹兹堡和前端范围GigaPoP及其周围，选定的直接连接的校园，以及合作者附近的其他几个关键地点。原型诊断基础设施将用于通过招募实际最终用户、应用程序设计人员和网络管理员对我们的工具进行现场测试来验证我们的诊断套件。这项工作将效仿Web100项目的“早期采用者”工作。总而言之，在更大的互联网中，有大量的性能问题仍然隐藏着，因为它们在较短、低延迟的路径上测试时不会显示任何症状。这里的目标是通过适当地补偿延迟和消除短路径的错误阳性诊断结果来革命性地进行互联网性能诊断，从而产生有效的广域网诊断策略。

A critical missing piece of the end-to-end network performance puzzle stems from the fact that current network diagnostic strategies do not adequately take into account the effects of path delay. This is a proposal to develop extensions to existing diagnostic tools which will take path delay into consideration effectively, compensate for a variety of delay times, and test the effects of these new diagnostic tools with network users and operators using actual high performance applications. End-to-end Internet diagnosis is such a difficult problem because the symptoms of nearly all flaws scale with path delay and the symptoms that scale with delay cause classical diagnostic strategies to yield misleading results. Classical diagnostic tools and strategies yield confusing results because merely changing the path delay changes the symptoms of the flaws, even though the flaws are not in the additional part of the path. This new diagnostic methodology uses several different techniques to compensate for the effects of path delay on diagnostic results: Emulated Delay, which uses specialized software to buffer and delay packets as though they traverse a long path, Parametric Model Scaling, a method of verifying that a short path can support TCP bulk transport over a long path by verifying that the short path implements the required properties for TCP to meet the end-to-end performance objective, and "Scenic" Virtual Private Networks, where packets can be delayed by using various IP tunnels or virtual private networks to send them on long "scenic" alternate routes. These techniques will be used in conjunction with existing diagnostic tools and strategies. This project will develop a suite of enhanced diagnostic tools that compensate for the effects of path delay. This suite will be targeted at several different audiences: true end users, application developers, network administrators and diagnostic experts or tool developers. The suite will be built from a small kit of core components that implement the previously described techniques that compensate for path delay, in conjunction with some simple diagnostic applications. A prototype diagnostic infrastructure consisting of diagnostic servers and test targets placed in the network will be deployed. The prototype diagnostic infrastructure will be deployed in and around the Pittsburgh and the Front Range GigaPoPs, selected directly connected campuses, as well as at a few other key sites near collaborators. The prototype diagnostic infrastructure will be used to validate our diagnostic suite by recruiting real end users, application designers and network administrators to field test our tools. This effort will be patterned after the "early adopter" effort of the Web100 project. In summary, there are a vast number of performance problems in the greater Internet that remain hidden because they do not exhibit any symptoms when tested on short, low delay, paths. The goal here is to revolutionize Internet performance diagnosis by properly compensating for delay and eliminating false positive diagnostic results for short paths, resulting in effective diagnostic strategies for Wide Area Networks.