Internet Outages

Observing the CenturyLink outage on 2020-08-30

CenturyLink / Level3 was reported to have a major outage on Sunday, 2020-08-30 (as reported on CNN and discussed on slashdot).

This outage was very clear in our Trinocular near-real-time outage detection system. We have summarized the details with images, before, during, and after, and an animation of the nearly 7-hour event or see the event on our near-real-time outage website.

This outage is one of the largest U.S. nation-wide events since the 2014-08-27 Time Warner outage.

Announcements Outages

new website for browsing Internet outages

We are happy to announce a new website at that supports our Internet outage data collected from Trinocular.

The ANT Outage world browser, showing Hurricane Irma just after landfall in Florida in Sept. 2017.

Our website supports browsing more than two years of outage data, organized by geography and time.  The map is a google-maps-style world map, with circle on it at even intervals (every 0.5 to 2 degrees of latitude and longitude, depending on the zoom level).  Circle sizes show how many /24 network blocks are out in that location, while circle colors show the percentage of outages, from blue (only a few percent) to red (approaching 100%).

We hope that this website makes our outage data more accessible to researchers and the public.

The raw data underlying this website is available on request, see our outage dataset webpage.

The research is funded by the Department of Homeland Security (DHS) Cyber Security Division (through the LACREND and Retro-Future Bridge and Outages projects) and Michael Keston, a real estate entrepreneur and philanthropist (through the Michael Keston Endowment).  Michael Keston helped support this the initial version of this website, and DHS has supported our outage data collection and algorithm development.

The website was developed by Dominik Staros, ISI web developer and owner of Imagine Web Consulting, based on data collected by ISI researcher Yuri Pradkin. It builds on prior work by Pradkin, Heidemann and USC’s Lin Quan in ISI’s Analysis of Network Traffic Lab.

ISI has featured our new website on the ISI news page.


In-the-news Internet Outages

Evaluation of Hurricane Harvey’s Effects on the Internet’s Edge

On August 25, 2017 Hurricane Harvey made landfall in south Texas, causing widespread property damage, displacing more than 30,000 people, and costing more than 45 lives (as of 2017-09-01).

We sympathize with those were hurt by this disaster, and hope for swift recovery for the region.

We recently examined the effects of Hurricane Harvey on the area using Trinocular, our internet outage detection system.  Two key results:

Trinocular report on outages in Texas after Hurricane Harvey (on 2017-08-28t03:32Z)

We see that landfall was followed by widespread Internet outages in the Corpus Christi area, with 40% or more home networks dropping off the Internet.

We see that over the following days, network outages grew in the Houston area, with many networks dropping off the Internet. However, the fraction of networks lost in Houston was much smaller than in the Corpus Christi area.

More details are on our Hurricane Harvey web page.  We will update that page as we get more data in.

The dataset including Hurricane Harvey will be internet_outage_adaptive_a29all-20170702 and will be released in October 2017. Until the full data is released, we have a preliminary dataset through August 2017 available on request.

Announcements Collaborations Data Internet Outages

welcoming Greece to the ANT Internet Census

We’re happy to welcome Greece to our browsable Internet map at !  Of course Greece has always been in our Internet censuses, but George Xylomenos and George Polyzos of the Athens University of Economics and Business (their lab) helped set up a new observation site.  Greece now provides a new vantage point for Internet censuses.

The differences in the census are small, as one would hope, since it’s a global Internet.  However, when we look at latency (the time it takes for an IP address to reply to our requests), Greece gives us a European view.

Compare the lower-left corner of the Internet, since that is European IPv4 address space:

it61g RTTs
Round-trip times from our Greek vantage point (in to the world. Observe that European IP addresses in the lower left corner are nearby (light colored).

it61w RTTs
Round-trip times from our Los Angeles-based vantage point (at to the world. Observe that European IP addresses in the lower left corner are distant (darker gray).

In addition to big thanks to George Xylomenos and George Polyzos of AUEB (σας ευχαριστώ!) and AUEB for institutional funding for this work.  We also thank Christos Papadopoulos (Colorado State) for helping with many details, and Colin Perkins (U. Glasgow) for discussions about potential European hosts.

Data from our Greece census is available to researchers at no cost on the same terms as our existing census data.  See our datasets page for details. Greek data starts with it61 as of 2014-08-29.