Industry Insight

Deep-sea cables key to keeping internet afloat

A fishing boat drops anchor for the night off the coast of Sydney — it’s something the crew has done multiple times a day for the past decade, and there’s nothing out of the ordinary with this particular drop. Yet unbeknown to them, this time the anchor severs a nondescript cable lying across the sea floor.

Immediately, people all around Australia notice their internet slows to a crawl as they try and access applications and websites hosted overseas. They begin complaining to their internet service providers (ISPs), which sets off a chain of events that — even when the priority to fix it is elevated to urgent — can only be corrected within a matter of weeks at best.

The anchor in this hypothetical scenario has severed a submarine fibre-optic cable that lies on the sea floor and transports internet traffic between Sydney and Asia. These cables are no thicker than a garden hose, and there are hundreds of them criss-crossing the globe.

They’re the primary reason you’re able to connect to applications and websites from anywhere in the world. Even when you’re on your smartphone accessing overseas content, that internet is provided by a mobile tower that connects to a terrestrial cable, which connects to the rest of the world via a subsea link at some point.

It’s estimated 95 per cent of all internet traffic comes to you at some stage via a submarine cable — yet most people think the internet is delivered via satellite.

These cables are critical to the modern globalised economy, but they’re at risk of damage from weather, subsea landslides, the occasional earthquake and, yes, the dropping of anchor by a trawling vessel. And the world has seen a few outages lately that have put submarine cables in the spotlight.

Recently a typhoon off Hong Kong caused six cable breaks, one of which connects Perth to Singapore and affected the services of at least two Australian ISPs.

It’s not an isolated outage, by the way: from 2008 to 2015 there have been 1218 recorded faults, so lapses are not new and continue to arise at the same rate, but in an era in which our reliance on connectivity is more important than ever, and increasingly so.

So why do we do it this way? Surely, with technological advances, there’s a better way to transport our internet?

The fact is fibre-optic cabling is the fastest way to deliver internet across the oceans, and nothing’s beating the speed of light anytime soon, which is the speed at which fibre optics can deliver data. Satellite delivery simply can’t match that speed or capacity.

The flip side of that is, yes, these cables are at the whim of typhoons, hurricanes, landslides and fishing and anchoring accidents, the latter of which account for some three-quarters of all outages.

So, how is a cable cut repaired?

Cable repair ships and crews are always on standby in strategic locations around the world and ready to mobilise within eight to 24 hours.

From there, while they know roughly where the cable cut has occurred and where the cable lies based on build charts, it’s no easy feat to locate a cable about the size of a garden hose that can be up to 7km below sea level. It can take half a day for the ship’s grapple — effectively a large, heavy hook that can grab and cut the cable and/or raise it — to simply sink to the sea floor.

Once the fault is identified, the cable has to be severed and a new piece spliced in. In deep water, there isn’t enough slack to raise a cable so it must be severed where it lies, using the grapple. Now, once the cable ends have been recovered to the water surface, they’ll be two times the water distance apart; that is, if the cable is in water 7km deep, then the two ends will be 14km apart when recovered.

In that scenario, a new piece of cable has to spliced in across 14km.

I might need to remind you that this is all being done at sea, while trying to stay as stationary as possible against weather and currents. Particularly bad weather can cause the whole exercise to be abandoned as the ship takes shelter, only to resume when the weather clears, further adding to the delay in rectifying the fault.

It makes the planning of these cables so crucial — if we can find the safest and most benign route along which to deploy a cable, we give ourselves the best possible chance of avoiding a crippling fault. Our company recently completed a subsea survey for the Southern Cross Cables NEXT project, which mapped 15,000km of sea floor between Sydney, New Zealand and the Pacific Islands to Hermosa Beach in Los Angeles. We looked for any hazards such as seamounts, trenches and shipwrecks, and mapped the course for the cable to avoid these potential hazards. Having done so, we can now begin to deploy the cable that we expect to finish in 2019.

None of these tasks are minuscule, yet every part of this process is critical to ensuring your online video doesn’t buffer and your emails don’t struggle to download and reach destinations across the planet.

These cables are scattered across the globe and they’re 95 per cent of the reason your phone can connect to Facebook, your laptop to Microsoft 365, Google Docs and your gaming system to other gamers across the planet.

They’ve been planned meticulously and for the most part your internet provider will, or should, use multiple cables or a highly secure and reliable system to ensure traffic can be re-routed in the event of disaster.

So, when there’s an outage, trust us: it’s being repaired as quickly as is humanly possible and every effort has been made to avoid the outage in the first place.

After all, the global economy has begun to depend on these cables, even if the majority of us don’t even know they exist.

Written by Dean Veverka

The Australian Business Review, September 26, 2017

Dean Veverka is chief technology officer of Southern Cross Cables.

Tags: Access, Capacity, Company, Configuration, Environment, Network

Contact Us

For any Technical or Network queries about Southern Cross or its products, please contact:

David Clampett


Contact Us

For further information about Southern Cross and Media enquiries, please contact:

Rosemay Foot