NeTS-NR: Preemption and Adaptation for Next Generation Multiservice Networks

NeTS-NR：下一代多服务网络的抢占和适应

• 批准号: 0435247
• 负责人: Jaudelice de Oliveira
• 金额: --
• 依托单位: Drexel University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-15 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0435247&HistoricalAwards=false
• 关键词: NeTS; NR; Preemption; Adaptation; Next

The objective of this project is to investigate the combined use of adaptation and preemption mechanisms in the context of best-effort networks, such as the Internet, as complementary tools for reacting to the onset of congestion or link failure. In particular, adaptation is seen as a means of reacting to light congestion, while preemption is useful for heavy congestion or link failure. With adaptation, the link bandwidth is dynamically allocated among competing flows so as to maximize specified QoS metrics, where each stream maintains its current route. With preemption, however, flows are selected to be re-routed based on their assigned priority levels. While preliminary adaptation and preemption policies have each been studied independently, this research project includes a novel combination of these mechanisms into a robust congestion control mechanism capable of handling traffic changes of varying magnitude. In practice, adaptation is essentially a distribution of the excess bandwidth left over after each stream's minimum bandwidth requirements have been satisfied. Preemption is appropriate when the congestion level is too great for adaptation to be viable. Preemption, however, carries a potentially greater impact on network stability and can cause service disruption for the flows selected for rerouting. The goal of this research is to study the tradeoffs between adaptation and preemption both analytically, in simulation, and on a physical testbed. The conclusion will be a recommendation regarding the optimal congestion mechanism for various congestion regimes.

本项目的目的是调查在互联网等尽力而为网络的背景下，如何综合使用适应和抢占机制，作为应对拥塞或链路故障的补充工具。特别是，适应被视为对轻微拥塞做出反应的一种手段，而抢占对于严重拥塞或链路故障是有用的。通过自适应，链路带宽在相互竞争的流之间动态分配，以便最大化指定的QoS度量，其中每个流维护其当前路由。然而，在抢占的情况下，根据为其分配的优先级来选择要重新路由的流。虽然初步的自适应和抢占策略都是独立研究的，但本研究项目将这些机制的新组合包括到能够处理不同大小的流量变化的健壮拥塞控制机制中。在实践中，自适应本质上是在满足每个流的最小带宽要求之后分配剩余带宽。当拥塞水平太高而无法适应时，抢占是合适的。然而，抢占可能会对网络稳定性带来更大的影响，并可能导致选择用于重新路由的流的服务中断。本研究的目标是在分析、模拟和物理试验台上研究适应和抢占之间的权衡。结论将是关于各种拥堵机制的最优拥堵机制的建议。