Nerding Out With Undersea Cables

April 14, 2009

During our last class, we briefly looked into the SEACOM undersea cable that will finally bring wired internet access to all of eastern Africa. The fact that a huge part of Africa relies on satellite to connect to the internet completely blew my mind, and when I found that even our connection to the internet here in Boston tenuously relies on the well-being of a few bottleneck points I decided to do some more research into the history of the backbone of the World Wide Web.

I spoke to my dad, a professional nerd, about the topic, and he pointed me to one of Wired Magazine’s most famous articles . Admittedly, the article is a bit dated (December 1996), and if you want a nice overview of the infrastructure that supports the internet, this is definitely not it. But if you want to get a fantastic perspective on the business of connecting people to the internet and the history of creating the infrastructure necessary for a global telecommunications network (and have an hour or two to kill), this article is a must-read.

As not everyone has the time to read the article, I’ve pulled out several quotations I thought were particularly interesting. Some are facts, some are general issues that have come up in class, and all definitely inform discussion about the subject. The quotations are listed in the order they appear in the article.

– “There is also the obvious threat of sabotage by a hostile government, but, surprisingly, this almost never happens. When cypherpunk Doug Barnes was researching his Caribbean project, he spent some time looking into this, because it was exactly the kind of threat he was worried about in the case of a data haven. Somewhat to his own surprise and relief, he concluded that it simply wasn’t going to happen. ‘Cutting a submarine cable,’ Barnes says, ‘is like starting a nuclear war. It’s easy to do, the results are devastating, and as soon as one country does it, all of the others will retaliate.'”

– “As little slack as possible is employed, partly because cable costs a lot of money (for the FLAG cable [A cable running from London to Egypt to Thailand to Tokyo constructed in the late 1990’s], $16,000 to $28,000 per kilometer, depending on the amount of armoring) and partly because loose coils are just asking for trouble from trawlers and other hazards. In fact, there is so little slack (in the layperson’s sense of the word) in a well-laid cable that it cannot be grappled and hauled to the surface without snapping it.”

– [The following answers a question that seems to come up a lot: “Where do fiber-optic cables come from?”] “The question naturally arises: How does one go about manufacturing a hollow glass tube thinner than a hair? More to the point, how did they do it 100 years ago? After all, as Worrall pointed out, they needed to be able to repair these machines when they were posted out on Ascension Island. The answer is straightforward and technically sweet: you take a much thicker glass tube, heat it over a Bunsen burner until it glows and softens, and then pull sharply on both ends. It forms a long, thin tendril, like a string of melted cheese stretching away from a piece of pizza. Amazingly, it does not close up into a solid glass fiber, but remains a tube no matter how thin it gets.
Exactly the same trick is used to create the glass fibers that run down the center of FLAG and other modern submarine cables: an ingot of very pure glass is heated until it glows, and then it is stretched. The only difference is that these are solid fibers rather than tubes, and, of course, it’s all done using machines that assure a consistent result.”

– “As I started to realize, and as John Worrall and many other cable-industry professionals subsequently told me, there have been new technologies but no new ideas since the turn of the century. Alas for Internet chauvinists who sneer at older, “analog” technology, this rule applies to the transmission of digital bits down wires, across long distances. We’ve been doing it ever since Morse sent “What hath God wrought!” from Washington to Baltimore.”

– [This is potentially one contributing factor to why it has taken so long to run a cable to eastern Africa.] “… The survey team is keeping an eye on the results, watching for any formations through which cable cannot be run. These are found more frequently in the Indian than in the Atlantic Ocean, mostly because the Atlantic has been charted more thoroughly.”

– “This is a big problem for a few different reasons. One is that cables take a few years to build, and, once built, last for a quarter of a century. It’s not a nimble industry in that way. A PTT thinking about investing in a club cable is making a 25-year commitment to a piece of equipment that will almost certainly be obsolete long before it reaches the end of its working life. Not only are they risking lots of money, but they are putting it into an exceptionally long-term investment. Long-term investments are great if you have reliable long-term forecasts, but when your entire forecasting system gets blown out of the water by something like the Internet, the situation gets awfully complicated.”

– “The art of laying a submarine cable is the art of using all the special features of such a ship: the linear engines, the maneuvering thrusters, and the differential GPS equipment, to put the cable exactly where it is supposed to go. Though the survey team has examined a corridor many thousands of meters wide, the target corridor for the cable lay is 200 meters wide, and the masters of these ships take pride in not straying more than 10 meters from the charted route. This must be accomplished through the judicious manipulation of only a few variables: the ship’s position and speed (which are controlled by the engines, thrusters, and rudder) andthe cable’s tension and rate of payout (which are controlled by the cable engine).”


– Matt Nix


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