[repairing underwater cables, a complex and tedious job

Part of the African continent was cut off on Thursday, March 14, after four of the five undersea cables connecting West Africa to the global network snapped. If the various operators reacted quickly to redirect their flows and restore the network, it could take several weeks to repair the cables.

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After internet outages that affected many West African countries like the worst-affected Ivory Coast, Liberia, Burkina Faso, Guinea and Ghana, the situation gradually returned to normal. Of the five submarine cables connecting this part of the continent with Internet, four were damaged, including two of the largest companies, Orange and MTN. In most cases, this type of incident is caused by cables being torn by ship anchors, fishing vessel activity or by underwater ground movements.

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The outages mainly concern the West African Cable System, the Africa Coast to Europe cables, the tens of thousands of kilometers of SAT-3 and MainOne cables, which serve many countries along the West African coast and connect to Europe, particularly in Spain, UK and France.

Traffic was redirected to restore the network

To restore Internet access as quickly as possible, service providers reacted quickly. In the hours after the outage, South African company MTN assured that “ businesses ” was in progress for “ redirects traffic through alternate routes in the network “. So did Orange who immediately said ” mobilized to find solutions to reroute traffic and connect countries isolated by other routes “.

By redirecting flows, Internet providers were able to quickly stabilize the situation and restore satisfactory network access for most of the countries affected by this outage. MTN, for example, confirmed this Monday March 19 that it had “ successfully restored operations, recovering over three terabits per second of capacity » throughout its coverage area. ” Throughout this period, we have prioritized service restoration by quickly activating new cables to increase connectivity and create alternative routes, strengthening the resilience of our network ”, welcomed the South African operator.

Locate the incident for repair

Repairing them is now a priority for operators to avoid grid saturation, but it is a complex and tedious task. “ You need to start by precisely locating the cut, explains Stéphane Lelux, its president Tactis telecommunications company to the RFI microphone. A specialized vessel must then be sent to the site, which will have to pinpoint the location of the cables. This already takes a few days: three, four or even five days at most “.

These particular ships are what are called cable ships. They are designed to lay cables the size of garden hoses on the ocean floor, as well as repair them. Up to 2,000 meters deep, underwater robots are responsible for retrieving each end of the damaged cables, but beyond 2,000 meters, the situation becomes complicated. In this case, ” we work the old-fashioned way, with a hook that we leave lying on the bottom. We lift it up to reset the cable and once it's up we can see if we hit it right. », Didier Dillard, CEO of Orange Marine, one of dozens of companies in the world capable of repairing underwater cables, explained to the newspaper. The New Republic in 2023.

An operation which it can take several weeks »

Therefore, the time that repairs can take varies greatly. Once the cables are reassembled, ” we cut them cleanly and redo the welds on these cables which we join with a waterproof sleeve which we will then put back on the bottom of the sea. There we have four cables so four operations must be done. It may take several weeks ”, Stéphane Lelux estimates. Because optical fiber is very fragile, the process of re-soldering the fibers together can take 15 to 20 hours for each joint. Work performed by very specific personnel specially trained for this type of intervention.

Almost 99% of intercontinental Internet traffic supplied by submarine cables, so their importance is capital, particularly for Africa. The continent is is highly dependent on submarine cables, including continental connections. I think the lessons to be learned from all these incidents, which unfortunately will continue, are first of all to diversify the routes and strengthen the connections between countries. ”, concludes Stéphane Lelux.

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