John Cioffi, the Father of DSL
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Stanford Professor John Cioffi is world-renowned for his contributions to networking: He invented DSL, VDSL and Vectored DSL, and his work has led to more than 400 publications and more than a hundred patents. He’s been recognized throughout his career as a leader in the Internet space, and has received countless accolades, including being named an IEEE Fellow and a Marconi Fellow. In 2014 Cioffi was inducted into the Internet Hall of Fame.
Cioffi recently sat down with HTF Editor Richard Bennett for a wide-ranging discussion about Internet networking and the issues that face engineers and ISPs as they try to bring high-speed communications to the masses.
The transition from copper to fiber takes place incrementally, as the fiber gets built out from the network core toward business and residential users, Cioffi explains. On average, it can cost several thousand dollars to get fiber close to the individual user. “That’s what has prevented fiber from going all the way to the home throughout the world. Just a few countries have been able to do this effectively.”
Cioffi points to the United Arab Emirates as one example of a country that built out fiber to all it citizens — at a cost of $8,000 per customer. With a million customers, it cost the UAE $8 billion, which they afforded with government subsidies. “Subsidization by a wealthy country over a small population is one thing,” Cioffi says. “Subsidization for the US or China or Brazil over a hundred million connections or more, it doesn’t work. You get into trillions of dollars, and deficits of major countries could be erased for that kind of money. So it just doesn’t make economic sense to run fiber to every single customer.”
Many so-called fiber-to-the-home systems terminate with DSL. And sometimes it makes financial sense to build fiber to the basement of a building and then wire the units with copper DSL, which can provide up to 1 gigabit of speed, Cioffi says. But even then, he says, shared systems face bandwidth problems. Fiber buildouts share up to 32 customers on that fiber using a GPON (gigabit-capable Passive Optical Network), and even on fiber, speeds can be reduced to 1-2 Mbps if everyone in a building is using the Internet at the same time. In contrast, unlike cable, fiber and wireless, DSL is unshared — and Cioffi’s earlier 6Mbps DSL line actually provided better video quality than fiber!
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By the way, here’s the TV commercial SBC ran for DSL in the late 1990s. Enjoy.