These outages were nation-wide, apparently affecting most of Italy. However, it looks like they “only” affected 20-30% of networks, and not all Italian ISPs. We’re happy they were able to recover so quickly.
This event shows the importance of global network monitoring.
The Domain Name System (DNS) is an essential service for the Internet which maps host names to IP addresses. The DNS Root Sever System operates the top of this namespace. RIPE Atlas observes DNS from more than 11k vantage points (VPs) around the world, reporting the reliability of the DNS Root Server System in DNSmon. DNSmon shows that loss rates for queries to the DNS Root are nearly 10% for IPv6, much higher than the approximately 2% loss seen for IPv4. Although IPv6 is “new,” as an operational protocol available to a third of Internet users, it ought to be just as reliable as IPv4. We examine this difference at a finer granularity by investigating loss at individual VPs. We confirm that specific VPs are the source of this difference and identify two root causes: VP islands with routing problems at the edge which leave them unable to access IPv6 outside their LAN, and VP peninsulas which indicate routing problems in the core of the network. These problems account for most of the loss and nearly all of the difference between IPv4 and IPv6 query loss rates. Islands account for most of the loss (half of IPv4 failures and 5/6ths of IPv6 failures), and we suggest these measurement devices should be filtered out to get a more accurate picture of loss rates. Peninsulas account for the main differences between root identifiers, suggesting routing disagreements root operators need to address. We believe that filtering out both of these known problems provides a better measure of underlying network anomalies and loss and will result in more actionable alerts.
This work was done while Tarang was on his Summer 2022 undergraduate research internship at USC/ISI, with support from NSF grant 2051101 (PI: Jelena Mirkovich). John Heidemann and Yuri Pradkin’s work is supported by NSF through the EIEIO project (CNS-2007106). We thank Guillermo Baltra for his work on islands and peninsulas, as seen in his arXiv report.
Asma Enayet will present her poster “Internet Outage Detection Using Passive Analysis” by Asma Enayet and John Heidemann at ACM Internet Measurement Conference, Nice, France from October 25-27th, 2022.
Outages from natural disasters, political events, software or hardware issues, and human error place a huge cost on e-commerce ($66k per minute at Amazon). While several existing systems detect Internet outages, these systems are often too inflexible, with fixed parameters across the whole internet with CUSUM-like change detection. We instead propose a system using passive data, to cover both IPv4 and IPv6, customizing parameters for each block to optimize the performance of our Bayesian inference model. Our poster describes our three contributions: First, we show how customizing parameters allows us often to detect outages that are at both fine timescales (5 minutes) and fine spatial resolutions (/24 IPv4 and /48 IPv6 blocks). Our second contribution is to show that, by tuning parameters differently for different blocks, we can scale back temporal precision to cover more challenging blocks. Finally, we show our approach extends to IPv6 and provides the first reports of IPv6 outages.
This work was supported by NSF grant CNS-2007106 (EIEIO).
The Covid-19 pandemic disrupted the world as businesses and schools shifted to work-from-home (WFH), and comprehensive maps have helped visualize how those policies changed over time and in different places. We recently developed algorithms that infer the onset of WFH based on changes in observed Internet usage. Measurements of WFH are important to evaluate how effectively policies are implemented and followed, or to confirm policies in countries with less transparent journalism.This paper describes a web-based visualization system for measurements of Covid-19-induced WFH. We build on a web-based world map, showing a geographic grid of observations about WFH. We extend typical map interaction (zoom and pan, plus animation over time) with two new forms of pop-up information that allow users to drill-down to investigate our underlying data.We use sparklines to show changes over the first 6 months of 2020 for a given location, supporting identification and navigation to hot spots. Alternatively, users can report particular networks (Internet Service Providers) that show WFH on a given day.We show that these tools help us relate our observations to news reports of Covid-19-induced changes and, in some cases, lockdowns due to other causes. Our visualization is publicly available at https://covid.ant.isi.edu, as is our underlying data.
I would like to congratulate Dr. Hang Guo for defending his PhD in April 2020 and completing his doctoral dissertation “Detecting and Characterizing Network Devices Using Signatures of Traffic About End-Points” in May 2020.
From the abstract:
The Internet has become an inseparable part of our society. Since the Internet is essentially a distributed system of billions of inter-connected, networked devices, learning about these devices is essential for better understanding, managing and securing the Internet. To study these network devices, without direct control over them or direct contact with their users, requires traffic-based methods for detecting devices. To identify target devices from traffic measurements, detection of network devices relies on signatures of traffic, mapping from certain characteristics of traffic to target devices. This dissertation focuses on device detection that use signatures of traffic about end-points: mapping from characteristics of traffic end-point, such as counts and identities, to target devices. The thesis of this dissertation is that new signatures of traffic about end-points enable detection and characterizations of new class of network devices. We support this thesis statement through three specific studies, each detecting and characterizing a new class of network devices with a new signature of traffic about end-points. In our first study, we present detection and characterization of network devices that rate limit ICMP traffic based on how they change the responsiveness of traffic end-points to active probings. In our second study, we demonstrate mapping identities of traffic end-points to a new class of network devices: Internet-of-Thing (IoT) devices. In our third study, we explore detecting compromised IoT devices by identifying IoT devices talking to suspicious end-points. Detection of these compromised IoT devices enables us to mitigate DDoS traffic between them and suspicious end-points.
Hang defend his PhD when USC was on work-from-home due to COVID-19, so he is the first ANT student with a fully on-line PhD defense.
John Heidemann gave the talk “A First Look at Measuring the Internet during Novel Coronavirus to Evaluate Quarantine (MINCEQ)” at Digital Technologies for COVID-19 Webinar Series, hosted by Craig Knoblock and Bhaskar Krishnamachari of USC Viterbi School of Engineering on May 29, 2020. Internet Outages: Reliablity and Security” at the University of Oregon Cybersecurity Day in Eugene, Oregon on April 23, 2018. A video of the talk is on YoutTube at https://www.youtube.com/watch?v=tduZ1Y_FX0s. Slides are available at https://www.isi.edu/~johnh/PAPERS/Heidemann20a.pdf.
From the abstract:
Measuring the Internet during Novel Coronavirus to Evaluate Quarantine (RAPID-MINCEQ) is a project to measure changes in Internet use during the COVID-19 outbreak of 2020.
Today social distancing and work-from-home/study-from-home are the best tools we have to limit COVID’s spread. But implementation of these policies varies in the US and around the global, and we would like to evaluate participation in these policies. This project plans to develop two complementary methods of assessing Internet use by measuring address activity and how it changes relative to historical trends. Changes in the Internet can reflect work-from-home behavior. Although we cannot see all IP addresses (many are hidden behind firewalls or home routers), early work shows changes at USC and ISI.
This project is support by an NSF RAPID grant for COVID-19 and just began in May 2020, so this talk will discuss directions we plan to explore.
This project is joint work of Guillermo Baltra, Asma Enayet, John Heidemann, Yuri Pradkin, and Xiao Song and is supported by NSF/CISE as award NSF-2028279.
Today, outage detection systems can track outages across the whole IPv4 Internet—millions of networks. However, it becomes difficult to find meaningful, interesting events in this huge dataset, since three months of data can easily include 660M observations and thousands of outage events. We propose an outage reporting system that sifts through this data to find the most interesting events. We explore multiple metrics to evaluate interesting”, reflecting the size and severity of outages. We show that defining interest as the product of size by severity works well, avoiding degenerate cases like complete outages affecting a few people, and apparently large outages that affect only a small fraction of people in an area. We have integrated outage reporting into our existing public website (https://outage.ant.isi.edu) with the goal of making near-real-time outage information accessible to the general public. Such data can help answer questions like “what are the most significant outages today?”, did Florida have major problems in an ongoing hurricane?”, and “are there power outages in Venezuela?”.
DNS depends on extensive caching for good performance, and every DNS zone owner must set Time-to-Live (TTL) values to control their DNS caching. Today there is relatively little guidance backed by research about how to set TTLs, and operators must balance conflicting demands of caching against agility of configuration. Exactly how TTL value choices affect operational networks is quite challenging to understand due to interactions across the distributed DNS service, where resolvers receive TTLs in different ways (answers and hints), TTLs are specified in multiple places (zones and their parent’s glue), and while DNS resolution must be security-aware. This paper provides the first careful evaluation of how these multiple, interacting factors affect the effective cache lifetimes of DNS records, and provides recommendations for how to configure DNS TTLs based on our findings. We provide recommendations in TTL choice for different situations, and for where they must be configured. We show that longer TTLs have significant promise in reducing latency, reducing it from 183ms to 28.7ms for one country-code TLD.
We have also reported on this work at the RIPE and APNIC blogs.
Ryan Bogutz completed his summer undergraduate research internship at ISI this summer, working with John Heidemann and Yuri Pradkin on his project “Identifying Interesting Outages”.
In this project, Ryan examined Internet Outage data from Trinocular, developing an outage report that summarized the most “interesting” outages each day. Yuri integrated this report into our outage website where is available as a left side panel.
We hope Ryan’s new report makes it easier to evaluate Internet outages on a given day, and we look forward to continue to work with Ryan on this topic.
Ryan visited USC/ISI in summer 2019 as part of the (ISI Research Experiences for Undergraduates. We thank Jelena Mirkovic (PI) for coordinating the second year of this great program, and NSF for support through award #1659886.