In deep: the internet’s underwater weak links

While many of us are busy worrying about an internet apocalypse at the hands of IoT bots, there are many other ways the global network could be brought to its knees. A little over 350 of them, in fact, are lying at the bottom of the ocean.

Submarine cables stretch across the world, managing almost all the internet’s traffic between them. That’s everything from financial settlement systems through to voice and video calls.

Content distribution networks help to take the load off both systems by situating oft-repeated content closer to its audience, but it must still get to those staging points in the first place.

Typically, when a submarine cable goes down the causes are mundane. A ship dragging its anchor along the seabed was reportedly responsible for cutting direct connections between the UK mainland and the Channel Islands in late November, for example. As a result, telecoms firm JT had to route all traffic to and from the Channel Islands via an alternative link with France.

When human ineptitude isn’t to blame for submarine cable outages, it’s most often nature – earthquakescyclones and the like – that take over. But what about intentional human intervention?

We have seen signs of attacks in the past, such as the incident in Egypt in 2013, when three divers were caught attempting to cut undersea cables (although they later said it was a mistake).

Analysts tell us that simple redundancy will protect us, and as the Channel Islands incident showed, there are typically multiple points of redundancy in undersea fibre-optic networks.

These levels of redundancy vary around the world, though, with historically proven single points of failure at several locations along the top of Africa and in south-east Asia.

Even in countries with more developed connections, targeting multiple ingress and egress points could create significant service disruptions.

We have seen what appear to be malicious attacks on cables before. In 2008, the cables connecting Sicily to Egypt were cut, reportedly choking off traffic between Europe and Asia.

Submarine cables are unprotected in deep waters, simply lying on the seafloor. Closer to the coastline, they are often protected by a galvanized coating and shallowly buried.

Then they come ashore, often connecting to terrestrial fibre underneath access covers next to the beach or in small, anonymous-looking concrete buildings.

All these points are potentially vulnerable to different kinds of physical attack.

Experts point out that submarine cables can always be repaired. The question is, how long would this take? It took around two weeks to get the three severed Channel Islands cables back up and running – though this was partly because the ship originally assigned to the job was called away to another.

There are only so many vessels able to perform this highly specialized job, and they’ve been known to face attacks of their own. What would happen if the global fleet were taxed too heavily?

While it may sound like the plot of a Bond movie, the reality is, such attacks are enough of a threat that the Pentagon is taking notice. Recent reports suggest that the US is getting particularly worried about Russian submarine and spy ship activities around undersea cable routes.

Companies such as Microsoft and Google are building out their own submarine fibre, probably more for cost reasons than for resiliency.

On land, and over short stretches of water such as the English Channel, microwave is also proving a lower-latency option than fibre for companies particularly worried about that kind of thing.

Neither hyperscale-owned fibre or bank-commissioned microwave may be predicated on resiliency but it’s certainly a side benefit. For those companies not rich enough to build out their own private internet backbone, however, a little planning might be necessary to ensure that traffic is channelled along several redundant routes.

While corporate providers mull these options, consumers will just have to cross their fingers and hope for the best when they settle down to a video call with Grandma half a world away.