Tag Archives: internet

YouTube Access Denied

Millions of users around the globe could not access YouTube for a couple hours yesterday. Why?

Well to understand, we need to start with how you normally connect to a web site. You click on a link to youtube.com. Your ISP looks up the internet address for youtube.com by looking at internet routing tables. Each domain has a name server that provides the IP address for where it should be found (for example, an IP address that shows youtube.com is 208.65.153.238).

Well what happened in this case is Pakistan decided to prevent anyone in Pakistan from accessing YouTube because the government didn’t like some video. The way Pakistan decided to accomplish this was to update their routing table to just direct all traffic that was meant to go to YouTube to a phony address which would then return nothing.

Why did many outside of Pakistan lose access to YouTube? Well their version of the routing table leaked out of Pakistan through PCCW (large internet provider), Then other internet providers adopted the incorrect information, until many around the globe were being directed to the wrong place.

You might find it amazing the routing system could allow such a thing to happen – it doesn’t seem very secure. You are right, that it doesn’t seem very sensible. When the internet was created some protocols were established that made sense then but don’t necessarily make sense for what the internet has become.

The problem was fixed when Google’s YouTube engineers contacted PCCW to inform them of the problem and have them correct it. I think if it was my site instead, I would have had difficulty figure out what was going on 🙂 Once PCCW corrected their routing tables the fixed flowed through the system and everyone was able to see the great stuff like Marissa Mayer discussing Innovation at Google.

I would imagine Internet2 (well on its way to a computer near you) and IPv6 will take not be so venerable to such a mistake.

Internet Undersea Cables

In a previously post we highlighted some of the engineering involved in fixing undersea cables and the challenges in laying internet fiber underwater. Given the recent news those posts might be of interest: Cut undersea Internet cables slow India’s connectivity

Early estimates suggested that half of India’s Internet capacity vanished after the first two cable lines were cut Wednesday. In other countries, such as Egypt, the figure was as high as 70 percent. The two Mediterranean cables cut Wednesday carry the bulk of the region’s Internet traffic
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Much of this traffic has now been rerouted along Pacific cables. Because of the redirected traffic, a third cable cut, discovered Friday in the Gulf region, has had no effect. Some 90 percent of India’s bandwidth has been restored and cable repairs are expected to take two weeks, but bad weather has prevented a repair ship from setting off to mend one of the cables.

For some businesses, the cut meant a slightly degraded service – poorer reception for call-centers that use Internet telephony, for example. But for larger businesses that carry the bulk of outsourcing from the United States and Europe, there was virtually no disruption.

“We have diversity in path and providers globally, and hence we have not lost any connectivity to our offices or customers,” according to an e-mailed statement by Infosys, one of India’s largest Information Technology companies.

While the initial reports talk of the cables being damaged by a ship anchor, at least one new report disputes that, Ships did not cut internet cable:

No ships were present when two marine cables carrying much of the Middle East’s internet traffic were severed, Egypt’s Ministry of Communications has said, contrary to earlier speculation about the causes of the cut.
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“A marine transport committee investigated the traffic of ships in the area, 12 hours before and after the malfunction, where the cables are located to figure out the possibility of being cut by a passing vessel and found out there were no passing ships at that time,” said the statement.

Harvard Course: Understanding Computers and the Internet

Harvard Extension School – Computer Science E-1: Understanding Computers and the Internet

This course is all about understanding: understanding what’s going on inside your computer when you flip on the switch, why tech support has you constantly rebooting your computer, how everything you do on the Internet can be watched by others, and how your computer can become infected with a worm just by turning it on. In this course we demystify computers and the Internet, along with their jargon, so that students understand not only what they can do with each but also how it all works and why. Students leave this course armed with a new vocabulary and equipped for further exploration of computers and the Internet. Topics include hardware, software, the Internet, multimedia, security, website development, programming, and dotcoms. This course is designed both for those with little, if any, computer experience and for those who use a computer every day.

Nice job. via: Learn How The Darn Thing Works … from Harvard

The Web is 15 Years Old

How the web went world wide

Many users know that Sir Tim Berners-Lee developed the web at the Cern physics laboratory near Geneva.
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One key date is 6 August 1991 – the day on which links to the fledgling computer code for the www were put on the alt.hypertext discussion group so others could download it and play with it.

So, in 1991, the web protocol was added to the internet which was created by the United States ARPA and DARPA starting in 1968, or so depending on what is counted as the start.

Additional articles exploring the history of the internet and the world wide web:

China Builds a Better Internet

China Builds a Better Internet (site broke the link so I removed it)

China is looking to become a scientific leader, with projects like China’s Next Generation Internet, to strengthen their economy by creating

its own scientific and technological breakthroughs—using a new and improved version of today’s dominant innovation platform, the Internet. “CNGI is the culmination of this revolutionary plan” to turn China into the world’s innovation capital, says Wu Hequan, vice president of the Chinese Academy of Engineering.
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The United States’ reluctance to invest in IPv6 makes it more likely that China will be in a position to gain the first-mover advantage it seeks. A draft version of a January 2006 report by the Department of Commerce on IPv6 contained a section on competitiveness that highlighted several threats to U.S. Internet leadership, including a further shift of high-tech R&D and product innovation eastward and less available investment capital because of the higher costs of maintaining IPv4 networks. What remains to be seen is whether China can develop the services that take advantage of the next-generation Internet. But China’s researchers are already working on it. At the IPv6 Global Summit in April, China’s major telecommunications and Internet companies got up on stage one by one and told the audience that they have research facilities dedicated to developing these services.

IPv6 is coming, in fact it is already here, though in a limited way. The work started in 1994 when the IPv6 working group was established and proposed standard adopted by the Internet Engineering Steering Group.

IEEE-USA chief calls for IPv6 adoption:

Adoption of a next-generation Internet Protocol by China, Japan and South Korea and other Asian countries should raised questions about U.S. innovation policy, the president of IEEE-USA told an IPv6 conference here Friday

50 Top Science Blogs

50 Top Science Blogs (“by working scientist as far as they can tell”) based on technorati rank from Nature. Including:

Missing science blogs include:

Inky Circus (they actually rank high enough so the working scientist qualification must have eliminated them)
Curious Cat Science and Engineering Blog (we don’t rank high enough or meet the working scientist qualification 🙁 )