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How Google Cramming More Data Into Its New Atlantic Cable



Google says the fiber optic cable it's building across the Atlantic Ocean will be the fastest of its kind. When the cable goes live next year, the company estimates it will transmit around 250 terabits per second, fast enough to turn all the contents of the Library of Congress from Virginia to France three times every second. That's about 56 percent faster than Facebook and Microsoft's Sea cable, which can transmit around 160 terabits per second between Virginia and Spain.

Fiber-optic networks work by sending light over thin strands of glass. Fiber-optic cables, which are about the diameter of a garden hose, enclose multiple pairs of these fibers. Google's new cable is so fast because it carries more fiber pairs. Today, most long-distance undersea cables contain six or eight fiber-optic pairs. Google said Thursday that its new cable, dubbed Dunant, is expected to be the first to include 1

2 pairs, thanks to the new technology developed by Google and SubCom, which designs, manufactures, and deploys undersea cables

Dunant might not be the NEC says it has technology that will allow long-distance undersea cables with 16 fiber-optic pairs. And Vijay Vusirikala, Head of Network Architecture and Optical Engineering at Google, says the company is already contemplating 24-pair cables.

The surge in intercontinental cables, and their increasing capacity, reflects the continuous growth in internet traffic. They enable activists to live protesters to distant countries, help companies buy and sell products around the world, and facilitate international romances. "Many people still believe that international telecommunications are conducted by satellite," says Atsushi Kuwahara, NEC executive director. "That was true in 1980, but nowadays, 99 percent of international telecommunications is a submarine."

So much capacity is being added that, for the time being, it is outstripping demand. Animations featured in a recent New York Times article illustrated the exploding number of undersea cables since 1989. That growth is continuing. Alan Mauldin of the Telegeography research firm says about 30 percent of the potential capacity of major undersea cable routes is currently in use and more than 60 new cables are scheduled to enter service by 2021. That summons memories of the 1990s Dotcom Bubble, telecoms buried far more fiber in both the ground and the ocean than they would need for years to come.

A selection of fiber optic cable products made by SubCom

Brian Smith / SubCom

But the current growth in new cables are driving less than telcos, and more by companies such as Google, Facebook, and Microsoft, which are increasingly seeking bandwidth for streaming video, photos and other data scuttling between their global data centers. And experts say that as undersea cable technologies improve, it's not crazy for companies to build newer, faster routes between continents, even with so much fiber already laying idle in the ocean

Controlling Their Own Destiny

Mauldin says that although there is still a lot of capacity available, companies like Google and Facebook prefer to have dedicated capacity for their own use. That's part of why big tech companies either have invested in new cables through consortia, or in some cases built their own cables

"When we do our network planning, it's important to know if we have the capacity in the network , "says Google's Vusirikala. "One way to know is by controlling our own destiny by building our own cables."

Another factor is diversification. Having more cables means there are alternative routes for data if a cable breaks or malfunctions. At the same time, more people outside Europe and North America are tapping the internet, often through smartphones. That's why prompted companies to think about new routes, like between North and South America, or between Europe and Africa, says Mike Hollands, an executive at the European data center company Interxion. The United Kingdom has made it possible for both Facebook and Microsoft to travel faster to North Africa and Middle East, while also creating an alternate path to Europe in the event that one or more of the traditional routes were disrupted by something like a earthquake [19659009] Cost Per Bit

There are financial incentives for the tech companies as well. By the time they own the cables instead of leasing them from telcos, Google and other tech giants can potentially save money in the long term, Mauldin says.

The cost to build and deploy a new undersea cable is not dropping. But as companies find ways to pump more data through these cables more quickly, their value increases.

There are several ways to increase the performance of a fiber-optic communications system. One is to increase the energy used to push the data from one end to the other. The catch is that to keep the data signal from degrading, undersea cables need repeaters roughly every 100 kilometers, Vusirikala explains. Those repeaters amplify not only the signal, but any noise introduced along the way, diminishing the value of boosting the energy

Subcomm.

Subcomm

You can also increase the amount of data that each fiber pair within a fiber-optic cable can carry. A technique called "dense wavelength division multiplexing" now allows more than 100 wavelengths to be transmitted along a single fiber pair.

Or you can pack more fiber pairs into a cable. Traditionally, each pair in a fiber-optic cable requires its own repeater; those repeaters take up space inside the cable, so Kuwahara says adding more repeaters would require changes to the way cables are built, deployed, and maintained

To get around that problem, Google and SubCom are using a technique called space-division multiplexing (SDM) to use only eight repeaters with 12 fiber pairs. "This was in our toolkit before," says Mohs, but like other companies, Subcomm has a lot of things to do with it, says Subcomm CTO Georg Mohs.

NEC is taking a different route from Google and SubCom. Kuwahara says NEC is packing more fiber optic pairs into its cables by substantially shrinking its repeaters so they fit into existing equipment designs

Regardless of how companies like SubCom and NEC add more pairs, the result is the same: cables that can move more data than ever before.


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