Researchers map Internet's 'black holes'

You would think there should be a really sophisticated way of detecting an Internet black hole. There isn't.

Most users run into an Internet black hole when the Web site they want to access won't load or their e-mail seems to get swallowed up in cyberspace.

According to a research team at the University of Washington, something like that is happening a lot more often, and over much longer times, than anyone ever thought. And they've created an interactive, online map, updated every 15 minutes, that shows the Internet's trouble spots. Colored flags show problem areas, and list the IP addresses affected.

The map is the fruit of an Internet monitoring system, dubbed Hubble after the black-hole-searching space telescope. Launched September 17, 2007, Hubble uses several techniques to uncover and identify what are called reachability problems -- when one Internet address can't reach another, even when their physical link is operational. Traffic seems to simply disappear into a black hole.

"We found reachability problems to be more common, widespread and longer lasting than we had expected," according to the UW researchers in an online report. During one three-week period, Hubble found more than 31,000 reachability problems involving more than 10,000 Internet prefixes (with each prefix covering a group of IP addresses). More than 21,000 were reachable by some computers but not others. Nearly 5,000 were completely unreachable. Of the prefixes with problems, 58 per cent experienced only a single "reachability event," but 25 per cent experienced three or more, and 193 experienced at least 20.

Many were resolved in less than an hour, but more than 60 per cent (more than 19,000 events) lasted more than two hours, and nearly 10 per cent (2,940) lasted at least 24 hours. The median duration for partial-reachability events was 2.75 hours, for complete unreachability events, 3.5 hours. Nearly 1,700 prefixes were partially unreachable for more than 24 hours.

The UW researchers are presenting a paper on Hubble at the Usenix Symposium on Network Systems Design and Implementation in the US. The University of Washington has posted a short online article about the project.

You would think that ISPs would have some really sophisticated way of detecting a black hole and locating the region or router that's responsible for it. They don't.

In an online paper, the Hubble team notes that network administrators typically resort to mailing lists, such as those of the Internet Security Operations Task Force and the North American Network Operators Group. Unexplained outages repeatedly prompt pleas for help "with users asking whether others can reach their prefixes, or posting when they are unable to reach certain destinations, to ask if others see the same problem or know the cause," according to the Hubble document.

The extent and durability of these problems undermine a basic tenet of the Internet, that every address is reachable from every other address -- at least in theory. Since Hubble began, the system has uncovered nearly 885,000 black holes.

The ongoing data collection by Hubble is done with test messages and probes through PlanetLab, a global network of just over 800 academic, industry, and government computers organized for development of new network services. Hubble uses about 100 of these computers, in some 40 countries, to continually probe the Internet. According to the UW team, Hubble is able to reliably monitor about 90 per cent of the Internet.

The University of Washington Hubble team includes Ethan Katz-Bassett, Harsha V. Madhyastha, John P. John, Arvind Krishnamurthy, Thomas Anderson, and David Wetherall. All are members of the Department of Computer Science and Engineering (Wetherall is listed as also being with Intel Research).

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

John Cox

Network World
Show Comments

Brand Post

PC World Evaluation Team Review - MSI GT75 TITAN

"I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it."

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Product Launch Showcase

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?