Reassessing the Constancy of End-to-End Internet Latency
Reassessing the Constancy of End-to-End Internet Latency
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发表时间：
2021
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通讯作者：
Lily Davisson;Joakim Jakovleski;Nhiem Ngo;Chau Minh Pham;J. Sommers
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作者：
Lily Davisson;Joakim Jakovleski;Nhiem Ngo;Chau Minh Pham;J. Sommers
Zhang等人在2001年发表的论文“On the Constancy of Internet Path Properties”[1]使用部署在Internet中的一组适度主机来检查端到端数据包丢失，延迟和吞吐量的恒定性。在这项工作之后的时间里，互联网发生了巨大的变化，包括自治系统层次结构的重新关注和IPv6的部署增加等发展。在本文中，我们研究了端到端互联网延迟的恒定性，重新审视了早期研究的结果。我们使用RIPE Atlas的延迟测量，选择了一组124个锚点，这些锚点具有广泛的地理分布，并来自112个不同的自治系统。Zhang等人的早期工作依赖于变点检测方法来识别数学上恒定的时间段。我们重新实现了在早期工作中描述的两种方法，并将它们用于RIPE Atlas延迟测量。我们还使用了一个最近发表的方法（HMM-HDP），它直接支持RIPE Atlas API。比较三种变点检测方法，我们发现，在早期的工作中使用的两种方法可能会错过许多由常见的电平移位事件引起的变点。总的来说，我们发现最近提出的HMM-HDP方法表现得更好。此外，我们发现，延迟尖峰（由早期工作定义）比20年前的普遍程度低了一个数量级。我们还发现，最大无变化区域（CFRs）沿沿着路径，我们在今天的互联网上观察到的是大大长于2001年观察到的，无论使用的变点检测方法。特别是，在早期研究中，第50百分位数的最大CFR为30分钟，但我们的分析显示其为3天或更长时间。此外，我们发现CFR持续时间在过去5年中似乎稳步增加。
—A paper by Zhang et al. in 2001, “On the Constancy of Internet Path Properties” [1] examined the constancy of end-to-end packet loss, latency, and throughput using a modest set of hosts deployed in the Internet. In the time since that work, the Internet has changed dramatically, including the flattening of the autonomous system hierarchy and increased deployment of IPv6, among other developments. In this paper, we investigate the constancy of end-to-end Internet latency, revisiting findings of the earlier study. We use latency measurements from RIPE Atlas, choosing a set of 124 anchors with broad geographic distribution and drawn from 112 distinct autonomous systems. The earlier work of Zhang et al. relies on changepoint detection methods to identify mathematically constant time periods. We reimplement the two methods described in that earlier work and use them on the RIPE Atlas latency measurements. We also use a recently- published method (HMM-HDP) that has direct support in a RIPE Atlas API. Comparing the three changepoint detection methods, we find that the two methods used in the earlier work may miss many changepoints caused by common level-shift events. Overall, we find that the recently proposed HMM-HDP method performs substantially better. Moreover, we find that delay spikes—as defined by the earlier work—are an order of magnitude less prevalent than 20 years ago. We also find that maximum change- free regions (CFRs) along paths that we observe in today’s Internet are substantially longer than what was observed in 2001, regardless of the changepoint detection method used. In particular, the 50 th percentile maximum CFR was on the order of 30 minutes in the earlier study, but our analysis reveals it to be on the order of 3 days or longer . Moreover, we find that CFR durations appear to have steadily increased over the past 5 years.