Fibre in the deep

The subsea cable system is probably the biggest physical part of the global telecom network, yet is obscure even to many in the industry, entering into public consciousness only during a major outage or when Google or Facebook invest in a new cable.

For what it's worth, it’s another part of traditional telecoms that is being subsumed by the internet. According to Telegeography 56% of the traffic on the trans-Atlantic route last year was carried by the big US internet firms and not telcos.  That number will only grow.

Though it is no longer the domain of a small club of telco execs, it’s always been a cosy sector, with its own technologies and business models, not to mention a culture of discretion: cables are critical yet lightly-protected infrastructure. As the Snowden revelations confirmed, their role can be highly political, too.

Notwithstanding all of those factors, there has been a spate of worthwhile reporting and analysis on the subsea networks in recent months.

Computer World here has taken the 60Tbps trans-Pacific FASTER cable backed by Google, KDDI and China Mobile as a way into a story about how cables get deployed:

About 6,000 kilometers of the cable has been loaded onto the cable ship René Descartes, which is docked at a submarine cable factory in Kitakyushu, southern Japan, operated by NEC group firm OCC. It will be the first time for the vessel, owned by French telecom firm Orange, and her crew to lay some 9,000 km of cable in one go.

One morning last week the slim cable, about 2 centimetres in diameter, was being loaded from the factory to the ship at its dock. Since the cable is mostly white and featureless, it takes a keen eye to see that it’s actually moving into the vessel, and rather quickly, on a long bed of rollers.

At 144.5 metres, the length of one and a half football fields, the René Descartes has three enormous tanks below its main deck into which the cable is being spooled.

The same author, Japan-based Tim Hornyak, has also written some fun facts about FASTER. Like that subsea cables are just 17mm thick and “have to withstand the pressure of 8 km of water on top of them, roughly the equivalent of putting an elephant on your thumb.”

Eaerlier this year New York academic Nicole Starosielski published a book, The Undersea Network, which explores the role of the subsea network and the cables themselves, as well as introducing some of the people managing them.

In this extract for the Scientific American, she stresses the fragility of the systems. An ops manager at a cable landing station points out that the number of faults falls over Christmas because “when you haven’t got people touching stuff it tends not to break.”

..there is a significant amount of human interpretation required to deduce the origin of a problem from an array of alarms. Cable engineers might be thought of as the doctors of the global cable network. Pointing to one rack, which has a light on, this technician says, “See… that machine is in a state of alarm.” He plugs in his computer to figure out what is wrong, but it remains unclear. He then turns to a rack from which several cords extend, plugging into another machine. He looks at the loose cords. “I think that this one here,” he says, picking up a cord, “is supposed to be in here”—he points to a jack— “but I’m not sure.” He’s not ready to risk it. This alarm is only for a backup machine, so it can wait. We leave the station, still not quite sure what the cause is, and head back to the network operations centre to consult with the other technicians. 

In another extract, posted on Motherboard, Starosielski observes that more than half of the world’s undersea cable landings are located on islands.

These include island nations (Japan and Indonesia), populous island cities (Hong Kong and Abu Dhabi) and less-intuitive cable hubs like Long Island (where much of New York’s traffic comes ashore). 

There are more landing points on the islands of Hong Kong and Taiwan than on the entire mainland of China. Fifteen cable systems connect Singapore to the network; only 13 are linked to the rest of mainland Southeast Asia. ..  Continents often depend on islands for their communication. All of Australia’s cable traffic passes through islands, which must remain above water and politically stable, before it reaches any other continent.

This appears to be a legacy of the British empire’s global telegraph system, where landing stations were sited on islands because they were more secure.

But in this article Starosielski examines a cable project on one island state, Tahiti. Although it already hosts a 640 Gbps cable running to Hawaii, it’s plotting another that, the author says, “would make Tahiti the central node in a trans-Pacific network, linking to South America on one side and China on the other.”

The political challenge this means to the US-driven status quo are obvious and mean it might not get laid.

Finally, if you’re yearning for a vicarious cable-laying adventure, Kristian Nielsen, a staffer at subsea consultancy WFN Strategies, shares his experiences on a cable ship installing the BLAST system in American Samoa.

With the floor sitting near to 4,000 meters deep, a truly staggering amount of “ultraline” and “uniline” was paid out to act as a bookmark for our installation progress. The process took the lion’s share of the day, capping-off just around sunset with a resounding “KABOOSH” as the buoy and associated tag lines splashed into the quickly darkening waters, armed only with a single strobe light to fight off the night.