The need for subsea network resiliency cannot be overemphasized when it comes to either moving huge amounts of data over transoceanic distances or ensuring the connectivity of a small community to the rest of the world. How can subsea network high availability and resiliency be achieved? It starts with the (technical) reliability of the various components subsea cable systems are made of. This includes not only the design and manufacturing of the submerged equipment but also its installation on the seabed and the proper design, manufacturing, and installation of the dry equipment (such as power feeding equipment and open cable interface) in the right environment (whether in a dedicated cable landing station or inside a data center). Even if properly designed and deployed, a submarine cable system can (and will likely in certain areas) suffer from external aggressions (the most common ones being due to fishing activities and ship anchoring) that may result in cable outage and traffic disruption.
The natural response of the industry to these unavoidable outages has been to deploy subsea cable networks (instead of individual, point-to-point cable systems) with protected or meshed architecture. This approach first led to the construction of transoceanic rings before the dotcom crash.
Figure 1: Two Examples of Trans-Pacific Cable Ring Architecture
Image courtesy of: www.submarinecablemap.com
Today, the favored approach is to build (or buy capacity/fibers on) several different point-to-point cable systems in order to assemble a subsea cable network with protection/restoration capabilities over physically diverted cable systems. On the most critical routes, the largest subsea capacity users tend to use at least three or four different physical paths to move their data between major traffic hubs. For instance, Hurricane Electric (one of the largest global IP Transit providers) has five separate 100G paths between the US and Europe.
February 2023: Vietnam Lost Subsea Connectivity to the Rest of the World
When it comes to subsea cable unavailability, the worst can always happen even in the case of multiple cable systems ensuring international connectivity. This was clearly illustrated in February 2023 when Vietnam lost subsea connectivity to the rest of the world after the failure (or severe down performance) of the AAE-1, AAG, APG, IA, and SMW-3 cable systems. These five international cable systems either suffered from serious failures and were completely unable to carry the Internet traffic or were only partly functional. In response to this situation, the Vietnamese Ministry of Information and Communications instructed domestic internet operators to cooperate to get access to international terrestrial capacity to offer an acceptable level of internet service traffic across the country.
Figure 2: The Five International Subsea Cable Systems Landing in Vietnam in Early 2023
Image courtesy of: www.submarinecablemap.com
The cable repairs took a long time due, in part, to the regional geopolitical situation to get permission from other countries to access the cable fault locations. Additionally, the Government of Vietnam felt that the international consortium-like ownership of these cables added a decision layer in the repair management process and did not prioritize Vietnamese interests. As a midterm solution, the Vietnamese Ministry has set a target for Vietnam to have ten international subsea cable systems in the next two years, of which three will be owned by domestic operators.
March 2024: Only One Subsea Cable Ensuring Direct Connectivity Between South Africa and Europe
Another example of a multi-cable-cut scenario in subsea cable networks happened on March 14, 2024. This time, the victim is South Africa, currently experiencing severe degradations in its direct connectivity to Europe with (i) the loss of SEACOM/Tata connectivity on the east-Africa coast in the last week of February and (ii) the loss of ACE, SAT-3 and WACS connectivity on the west-Africa coast (in addition to the failure of MainOne cable connecting Nigeria, Ghana, Ivory Coast, and Senegal to Europe).
It is believed (but not 100% confirmed yet) that the SEACOM/Tata TGN-Eurasia cable was damaged in the Red Sea due to an anchor dragging the seabed; this anchor was dropped by the bulk carrier Rubymar after she was hit by a Houthi missile. The same anchor is also believed to have crossed an area in the Yemeni waters where AAE-1 and EIG cable systems were damaged as well.
The reasons for the multiple outages on subsea cables near Abidjan in Ivory Coast are still unknown at time of writing. In the meantime, several operators, including Microsoft and Vodacom, have confirmed these multiple cable outages have reduced the total capacity supporting their services. Consequences for the South African end-users include the inability to access Azure cloud platform’s portal, increased network latency or packet drops when accessing their cloud resources and cloud-hosted services, intermittent connectivity issues, inability to process payments, and inability to access many popular online services such as First National Bank, LinkedIn, WhatsApp, X (Twitter), or Xbox (in addition to Microsoft 365 and Microsoft Teams).
The figure below represents subsea cables already in commercial service. Consequently, 2Africa and the potential extension of PEACE Cable to South Africa are not represented. Also, only cables offering “direct” South Africa-Europe connectivity are shown here (SEACOM is prolonged with its own fiber pairs on TE North cable system for connectivity across Egypt to Europe in Marseille, France). EASSy cable system is not represented as it stops in Port Sudan, Sudan.
Figure 3: Direct South Africa-Europe Connectivity Before and on 14 March 2024
Images courtesy of: www.submarinecablemap.com
Significant maintenance activities are now expected to take place off the Ivory Coast in the very short term. For the repair of SEACOM/Tata cable in Yemeni waters, the cable repair will likely take more time considering the need for military protection and preliminary agreement with maintenance vessel insurers.
The South Africa situation highlights the need for (even) further cable diversity and also for terrestrial trans-African links connecting the east and west coasts for redirecting traffic in case of severe cable disruptions on either coast.
With the increasing dependence of our modern societies on digital services, diversity for international connectivity has become a requirement of the utmost importance. Subsea connectivity diversity can come in different flavors:
- Route diversity
- Cable diversity
- Provider diversity
In parallel with assistance on technical, commercial, contractual, and regulatory matters, it is Pioneer Consulting’s responsibility to guide and support our clients to meet their (and the industry’s) diversity requirements.
For comments or questions, please contact us via [email protected].