Two submarine cables are cut and the Internet in Africa falls into chaos, and there are cases where the delay is improved despite the cable disconnection



On Sunday, August 6, 2023, local time, a landslide occurred in one of the world's longest submarine canyons, cutting two critical submarine cables that provide Internet services to Africa. As a result, Internet

bandwidth has drastically decreased along the coast of West Africa, and Internet users in Africa are in great confusion. Kentik , which provides network monitoring and security services, has released its own analysis of the submarine cable disconnection that occurred in Africa.

Dual Subsea Cable Cuts Disrupt African Internet | Kentik Blog
https://www.kentik.com/blog/dual-subsea-cable-cuts-disrupt-african-internet/



On August 6, 2023, a landslide occurred in the Congo Valley, the world's longest submarine canyon, near the mouth of the Congo River , which straddles the Democratic Republic of the Congo and Angola. As a result, two submarine cables ' WACS ' with a total length of about 14,000 km connecting the west coast of England and South Africa and ' SAT-3 ' connecting the west coast countries of Portugal, Spain and South Africa were cut. The SAT-3 failed first, and a few hours later the WACS also failed.

The location of the Congo Canyon where the landslide occurred is as follows.


The dark blue part extending from the land to the sea in the image below is the Congo Valley.



The greatest threat to submarine cables, which are the infrastructure that forms the world's Internet network, is ``marine activity by humans''. The most common reason for cutting a submarine cable is that ``a fishing boat hooks an anchor on the submarine cable during fishing and cuts the cable''.

In 2008, a submarine cable in the Mediterranean Sea was cut due to this.

The second biggest threat to submarine cables is nature. Undersea cables are often severed by landslides and earthquakes that occur on the seafloor, and the Hengchun earthquake that occurred off the south coast of Taiwan in December 2006 severed several submarine cables. This has paralyzed the Internet communication network in East Asia.

The International Cable Protection Commission (ICPC) said about the impact of the Hengchun earthquake, ``There were 21 failures in 9 submarine cables, and it took 49 days using 11 ships to restore everything to normal. There was an announcement .



In addition, a Japanese speaker introduced efforts to repair submarine cables damaged by the 2011

Great East Japan Earthquake at Suboptic 2013, a submarine cable conference held in Paris in 2013. According to this, it seems that the Great East Japan Earthquake caused Japan's submarine cables to be dragged to the seabed by about 1 km per cable. In this case, the cable repair order is not according to contractual priorities, but based on where the cable ship can safely navigate while avoiding the radiation emitted by the malfunctioning Fukushima Daiichi nuclear power plant. It seems to have been decided.



This is not the first time that two submarine cables, SAT-3 and WACS, have been severed due to landslides. A study published in June 2021 reported that SAT-3 and WACS were damaged by a large-scale submarine landslide at the mouth of the Congo River in 2020.

Also, in 2022, an accident occurred in Egypt, Africa, where terrestrial cables were cut and several submarine cable services were temporarily suspended. At this time, Kentik independently analyzed the impact on network connectivity of major cloud providers such as AWS, Azure, and Google Cloud, proving once again that even major cloud services rely on submarine cables. .

The graph below shows the communication performance from the AWS region in Cape Town, South Africa to London, England when the submarine cable was cut on August 6, 2023. The graph shows the latency (delay) of the network, and you can see that the latency increases sharply in the red frame. This is because when routing AWS traffic from Cape Town to London, a cable failure occurred and a different route was adopted than usual, and the route lengthened the latency from '150 ms' to ' It seems that it has increased to 195 milliseconds.



On the other hand, the network latency from Cape Town to South Korea and Seoul in Asia has decreased from '386 ms' to '304 ms'. Regarding the reduction in latency, Kentik said, ``The longer and longer delay routes that are normally used may become unavailable, causing traffic to take a more straight and shorter path, resulting in shorter delays.'' is mentioned.



In addition, regarding 'the reason why traffic must pass through a route with a larger delay on a daily basis', Kentik said, 'In this case, the 'route with the lowest delay' connecting Cape Town and Seoul is because the cost is too high. ” explains.

The graph below monitors the network traffic when the submarine cable was cut in August 2023. Kentik data shows that South Africa's largest network operator is

Telkom SA , whose network has seen peak traffic drop by up to 20% after the undersea cable cut.



In Namibia, West Africa, government-owned telecom operator Telecom Namibia lost about two hours of

transit to major telecom providers Cogent and BICS after the undersea cable was cut. Telecom Namibia's network traffic was then restored using rerouted cables.



In the case of Telecom Namibia, the transit from AS174 (Cogent) and AS6774 (BICS) was lost around 17:30 local time on August 6th, and the transit from AS37468 (cable via Angola) was lost around 19:00 on August 6th. and restore network traffic.



The cable repair ship '

CS Leon Thevenin ', which is active in West Africa, anchored on the East Africa side and engaged in repairing another cable when SAT-3 and WACS were cut. Due to cable repair missions in East Africa, CS Leon Thevenin is unlikely to be involved in SAT-3 or WACS repair missions until September 2023.




West Africa's network traffic is distributed over other submarine cables, such as Google's Equiano cable, which opened in early 2023. Like WACS and SAT-3, Equiano is a submarine cable along the west coast of Africa, but has not been affected by submarine landslides, which Equiano client Liquid Dataport emphasizes . doing.



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