ITR: Collaborative Research in Internet Topology Models - A Foundation for Large-Scale Simulations

ITR：互联网拓扑模型的协作研究 - 大规模模拟的基础

• 批准号: 0082318
• 负责人: Kenneth Calvert
• 金额: $ 11.24万
• 依托单位: University of Kentucky Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2005-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0082318&HistoricalAwards=false
• 关键词: ITR; Collaborative; Research; Internet; Topology

Network simulation is an indispensable tool for researchers seeking to understand the principles of network architecture and protocol design. A key parameter in any moderate to large-scale simulation is the topology, i.e., the way the nodes of the network are organized and connected to each other. "Good" models for topology are essential for good simulations. The PIs have developed graph modeling software that currently is widely used as a tool for generating topologies, particularly models of large internetworks. The Georgia Tech Internet Topology Models (GT-ITM) package allows researchers to construct model topologies whose structure arguably resembles the node-level structure of the Internet: routers or switches, connected by (bidirectional) links, and grouped into domains. The GT-ITM software is included with "ns2" [2], the defacto open-source standard for network simulation. Despite the wide-spread use of GT-ITM, in general, and its transit-stub model, in particular, a number of critical and fundamental questions remain unanswered about network topology modeling. For example, 1)Topology models. Recent data indicates that the current Internet topology has some properties that are not well reflected in the transit-stub model of GT-ITM [17]. For example, features such as the exchanges where many transit domains come together are lacking. Are there "better" techniques to generate topologies intended to model the Internet? More fundamentally, how should a topology generation technique be evaluated (i.e., how is "better" measured)? 2)Topology scaling. Although strides are being made in supporting large-scale simulations [33], most researchers will continue to simulate their protocols on topologies that are smaller than the target operational large-scale networks. How should smaller topologies be configured so that they reasonable reflect their larger counterparts? Is there a theory of topology scaling that can provide the fundamental grounding for configuring topologies of various sizes? 3)Topology use. The PIs primary interest in topology modeling is to provide a foundation for large-scale simulations. Facilitating the use of topologies in simulations must go beyond providing theoretically sound models, however, and include a set of complementary tools for graph visualization, routing table construction, etc. What visualization tools are useful to researchers and assist in accurate intuitive understanding of underlying topology? How can different routing policies be effectively reflected in routing table construction? The researchers propose (1) to address these and other fundamental questions in the area of topology modeling and (2) to reflect their understanding in a set of topology tools and benchmarks made available to the research community at large. This work will build on the PIs prior experience in modeling internetworks. The proposed work will contribute to fundamental understanding in the area of topology modeling. The work will include a set of evaluation criteria to assess the quality of a topology generation method and improvements in topology models. The work will also produce an evolutionary theory of topology scaling, with implications for efficient simulation using topologies that are smaller than the target. In addition to contributions to fundamental understanding, a central component of the proposed work is a set of tools and benchmarks to be made available to the research community at large, following in the tradition of the GT-ITM suite. These tools will allow other researchers to generate topologies, assess the quality of candidate topology modeling methods, utilize benchmarks based on current and future technologies, and interact with a visualization of topology.

网络仿真是研究人员寻求理解网络体系结构和协议设计原理的不可或缺的工具。在任何中等规模到大规模的模拟中，一个关键参数是拓扑结构，即，网络节点的组织和相互连接方式。“好的”拓扑模型对于良好的仿真是必不可少的。 PI已经开发了图形建模软件，该软件目前被广泛用作生成拓扑结构的工具，特别是大型互联网络的模型。格鲁吉亚技术互联网拓扑模型（GT-ITM）软件包允许研究人员构建模型拓扑，其结构可以说类似于互联网的节点级结构：路由器或交换机，通过（双向）链路连接，并分组到域中。GT-ITM软件包含在“ns 2”中[2]，这是网络仿真的事实上的开源标准。 尽管广泛使用的GT-ITM，在一般情况下，特别是它的transit-stub模型，一些关键的和基本的问题仍然没有回答有关网络拓扑建模。比如说， 1)拓扑模型。最近的数据表明，当前的互联网拓扑结构具有一些在GT-ITM的transit-stub模型中没有很好反映的属性[17]。例如，缺乏许多过境域汇集在一起的交换机等功能。是否有“更好”的技术来生成用于建模Internet的拓扑？更根本的是，应该如何评估拓扑生成技术（即，如何衡量“更好”？ 2)拓扑缩放。虽然在支持大规模仿真方面取得了长足的进步[33]，但大多数研究人员将继续在比目标操作大规模网络更小的拓扑上模拟他们的协议。应该如何配置较小的拓扑，使它们合理地反映较大的拓扑？是否有一种拓扑扩展理论可以为配置各种大小的拓扑提供基础？ 3)拓扑使用。PI对拓扑建模的主要兴趣是为大规模仿真提供基础。促进在模拟中使用的拓扑结构必须超越提供理论上健全的模型，但是，并包括一组互补的工具，图形可视化，路由表的建设等，什么可视化工具是有用的研究人员，并协助准确直观的理解底层拓扑结构？如何在路由表构建中有效地反映不同的路由策略？ 研究人员建议（1）解决拓扑建模领域的这些和其他基本问题，（2）在一组拓扑工具和基准中反映他们的理解，这些工具和基准可供研究界广泛使用。这项工作将建立在PI在建模互联网之前的经验。 所提出的工作将有助于在该地区的拓扑建模的基本理解。这项工作将包括一套评估标准，以评估拓扑生成方法的质量和拓扑模型的改进。这项工作还将产生一个拓扑缩放的进化理论，与有效的模拟使用拓扑结构小于目标的影响。除了对基本理解的贡献外，拟议工作的一个核心组成部分是遵循GT-ITM套件的传统，向整个研究界提供一套工具和基准。这些工具将允许其他研究人员生成拓扑，评估候选拓扑建模方法的质量，利用基于当前和未来技术的基准，并与拓扑的可视化进行交互。