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JARING's link to the global Internet is over an undersea cable that co
FLAG facts
The FLAG system, that mother of all wires, starts at Porthcurno, England, and proceeds to Estepona, Spain; through the Strait of Gibraltar to Palermo, Sicily; across the Mediterranean to Alexandria and Port Said, Egypt; overland from those two cities to Suez, Egypt; down the Gulf of Suez and the Red Sea, with a potential branching unit to Jedda, Saudia Arabia; around the Arabian Peninsula to Dubai, site of the FLAG Network Operations Center; across the Indian Ocean to Bombay; around the tip of India and across the Bay of Bengal and the Andaman Sea to Ban Pak Bara, Thailand, with a branch down to Penang, Malaysia; overland across Thailand to Songkhla; up through the South China Sea to Lan Tao Island in Hong Kong; up the coast of China to a branch in the East China Sea where one fork goes to Shanghai and the other to Koje-do Island in Korea, and finally to two separate landings in Japan - Ninomiya and Miura, which are owned by rival carriers.
Phone company people tend to think (and do business) in terms of circuits. Hacker tourists, by contrast, tend to think in terms of bits per second. Converting between these two units of measurements is simple: on any modern phone system, the conversations are transmitted digitally, and the standard bit rate that is used for this purpose is 64 kbps. A circuit, then, in telephony jargon, amounts to a datastream of 64 kbps.
Copper submarine cables of only a few decades ago could carry only a few dozen circuits - say, about 2,500 kbps total. The first generation of optical-fiber cables, by contrast, carries more than 1,000 times as much data - 280 Mbps of data per fiber pair. (Fibers always come in pairs. This practice seems obvious to a telephony person, who is in the business of setting up symmetrical two-way circuits, but makes no particular sense to a hacker tourist who tends to think in terms of one-way packet transmission. The split between these two ways of thinking runs very deep and accounts for much tumult in the telecom world, as will be explained later.) The second generation of optical-fiber cables carries 560 Mbps per fiber pair. FLAG and other third-generation systems will carry 5.3 Gbps per pair. Or, in the system of units typically used by phone company people, they will carry 60,000 circuits on each fiber pair.
If you multiply 60,000 circuits times 64 kbps per circuit, you get a bit rate of only 3.84 Gbps, which leaves 1.46 Gbps unaccounted for. This bandwidth is devoted to various kinds of overhead, such as frame headers and error correction. The FLAG cable contains two sets of fiber pairs, and so its theoretical maximum capacity is 120,000 circuits, or (not counting the overhead) just under 8 Gbps of actual throughput.
These numbers really knock 'em dead in the phone industry. To the hacker tourist, or anyone who spends much time messing around with computer networks, they seem distinctly underwhelming. All this trouble and expense for a measly 8 Gbps? You've got to be kidding! Again, it comes down to a radical difference in perspective between telephony people and internet people.
In defense of telephony people, it must be pointed out that they are the ones who really know the score when it comes to sending bits across oceans. Netheads have heard so much puffery about the robust nature of the Internet and its amazing ability to route around obstacles that they frequently have a grossly inflated conception of how many routes packets can take between continents and how much bandwidth those routes can carry. As of this writing, I have learned that nearly the entire state of Mi
Douglas Barnes, an Oakland-based hacker and cypherpunk, looked into this issue a couple of years ago when, inspired by Bruce Sterling's Islands in the Net, he was doing background research on a project to set up a data haven in the Caribbean. "I found out that the idea of the Internet as a highly distributed, redundant global communications system is a myth,'' he discovered. "Virtually all communications between countries take place through a very small number of bottlenecks, and the available bandwidth simply isn't that great.'' And he cautions: "Even outfits like FLAG don't really grok the Internet. The undersized cables they are ru
So the bad news is that the capacity of modern undersea cables like FLAG isn't very impressive by Internet standards, but the slightly better news is that such cables are much better than what we have now.Here's how they work: Signals are transmitted down the fiber as modulated laser light with a wavelength of 1,558 nanometers (nm), which is in the infrared range. These signals begin to fade after they have traveled a certain distance, so it's necessary to build amplifiers into the cable every so often. In the case of FLAG, the spacing of these amplifiers ranges from 45 to 85 kilometers. They work on a strikingly simple and elegant principle. Each amplifier contains an approximately 10-meter-long piece of special fiber that has been doped with erbium ions, making it capable of functioning as a laser medium. A separate semiconductor laser built into the amplifier generates powerful light at 1,480 nm - close to the same frequency as the signal beam, but not close enough to interfere with it. This light, directed into the doped fiber, pumps the electrons orbiting around those erbium ions up to a higher energy level.
The signal coming down the FLAG cable passes through the doped fiber and causes it to lase, i.e., the excited electrons drop back down to a lower energy level, emitting light that is coherent with the incoming signal - which is to say that it is an exact copy of the incoming signal, except more powerful.
The amplifiers need power - up to 10,000 volts DC, at 0.9 amperes. Since public 10,000-volt outlets are few and far between on the bottom of the ocean, this power must be delivered down the same cable that carries the fibers. The cable, therefore, consists of an i