An Anti-Tromboning Policy – A Local Solution to Undersea Cable Threats

In 1992, when the first Internet eXchange Point (IXP) was launched, the goal was to streamline how networks shared and distributed traffic[1]. Similarly, when the Cameroon Internet Exchange Point (CAMIX) was setup by the Cameroon Ministry of Post and Telecommunications (MINPOSTEL), the goal was still the same. IXPs keep traffic […]

In 1992, when the first Internet eXchange Point (IXP) was launched, the goal was to streamline how networks shared and distributed traffic[1]. Similarly, when the Cameroon Internet Exchange Point (CAMIX) was setup by the Cameroon Ministry of Post and Telecommunications (MINPOSTEL), the goal was still the same. IXPs keep traffic local and route packets more efficiently between peer networks.

Cameroon, other parts of Africa and Asia have been experiencing significant disruption to Internet connectivity in the past few days attributed to the cut of at least three (4) undersea cables on the West African coast, including WACS, SAT-3 and Main One. While the actual cause of the damage is still unclear and is currently attributed to potential natural seabed movements, from an impact perspective, in Cameroon is reported losing USD 83,000 per day[2]. According to reports, services across all sectors were down, including banking services, e-commerce, money transfer and withdrawal, transport services, digitalised public services. This is concerning for a country whose digital transformation strategy aims to digitize the country and economy by 2035, including increasing the production and supply of digital content.

The wide impact on local services exposes the inefficient Internet connectivity design that is being used today, despite apparent progress made in using IXPs such as CAMIX to efficiently route packets. The design, where local traffic from one Internet Service Provider (ISP) to another local recipient’s ISP first leaves the country over a submarine cable before returning back to the country in a phenomenon called tromboning (see Figure 1).

Figure 1 Network Tromboning

A long time ago, when there was no domestic network infrastructure, no local content and little domestic traffic, it made sense then to use international transit networks such as undersea cables to connect between local service providers rather than build domestic infrastructure. But today, there is abundant local content, infrastructure and Internet eXchange Points in both Douala and Yaounde. Moreover, today Cameroon has local cloud flare servers, Google Content caches and Akamai caches which are all under or not utilized.

The debate that has unfolded online clearly points to the fact that internet connectivity, while on paper appears to be routing optimally, in reality it isn’t. Even the president of CAMIX confirmed this on his LinkedIn[3] page when he called for his peers (ISPs) to quickly exchange their traffic at the exchange point before they are disconnected and a recommendation for them to use local caching services so that their networks and users can continue communicating and accessing locally cached content and services despite the cable cuts. This way, users would not experience any disruptions unless they wanted to access international content not cached locally. This is indeed a practical solution where both the government and the private sector (local ISPs and content providers) have control over.

While redundancy would normally be the go-to solution where a single cable is cut, in this instance, three separate undersea cables connecting the continent’s west coast were cut. Moreover, earlier in March, a similar incident occurred on the other side of the continent (North-East coast) in the Red Sea where the anchor of a sinking ship hit by a missile fired by Houthi rebels cut at least four (4) underseas cables including SEACOM, TGN-Gulf, Asia-Africa-Europe-1 (AAE-1) and Europe (See Figure 2). That certainly makes redundancy over different undersea cables not the primary solution to Internet connectivity to local and cached content, IXPs are.

Figure 2 Affected Undersea Cables

At the international level, several solutions have been proposed. Including a call for countries to setup undersea cable surveillance capabilities, cable diplomacy and an international treaty against physical or cyberattacks on undersea cables. While there is no such treaty yet, there is however UN norms of responsible state behaviour in cyberspace which prohibits damaging critical infrastructure and calls for its protection from states[5].

While these international measures to protect undersea cable cables are essential, they do not solve the problem of accessing local and cached content during a catastrophic event out at sea or during unfortunate events such as this. If the reason for tromboning no longer exists, why then are Cameroonian networks still designed with such problematic design despite progress made in building local infrastructure and content? Does the sector require explicit anti-tromboning policies for it to design optimal and efficient networks?

Three years ago, MINPOSTEL authorized CAMIX to operate both the Yaounde and Douala IXPs. Yet, it seems from the president of the association’s post that this has done little to convince ISPs and content providers in Cameroon to use the infrastructure to peer directly and route local packets efficiently. In an article we wrote then[4] we argued that the lack of competition as a result of the model chosen by the government might see the cost of peering become expensive and deter ISPs from participating. Whatever the reason is, the scale of impact and the president’s message on LinkedIn certainly show that our concerns then were valid and that Cameroon’s Internet connectivity and peering design at its core hasn’t improved despite the deployment of the two government-owned Internet eXchange Points.

Perhaps, MINPOSTEL should use this incident to re-assess its strategy of CAMIX and internet infrastructure after three years of operations to see if it met the goals and objectives set out. In addition, MIMPOSTEL might need to find other ways – whether through incentives or policy – of getting ISPs to abandon the old tromboning design and move to local peering models that more accurately reflect the connectivity needs of the economy today and the aspirations of the country to become digitized by 2035. Finally, the government itself should perform an audit to determine where all local services such as security, customs, PII, and bank clearing services are hosted. A policy to host all such services locally in data centres around the country should be adopted.

While an anti-tromboning policy will provide resiliency for local and national traffic, submarine cables remain the best option for international connectivity. Satellite connection, could be used as backup for strategic and critical services but do not offer a sustainable alternative from a global perspective. For international connectivity, the need is firstly to implement efficient real-time high availability between our submarine cable connections: WACS, SAT3/WASC, SAIL, Cieba-2 and NCSCS. And secondly to establish connectivity and negotiate solid peering agreements with neighboring countries so that Cameroon can have a route to all international Submarines cables routes.

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[1] Danielle Jaccheo, “From NAPs to IXPs: A History of Peering,” 1623 Farnam (blog), August 1, 2023,

[2] “Internet Disruptions: More than Half a Billion CFA Francs Estimated Daily Losses for the Economy, 12.7 Million Cameroonians Affected – EcoMatin,” March 16, 2024,

[3] Olivier Leloustre, “(9) ‘Olivier Leloustre’ | Search | LinkedIn,” LinkedIn (blog), March 16, 2024,

[4] Tomslin Samme-Nlar and Isaac Noumba, “An Analysis of the Decision to Authorize CAMIX to Manage the Yaounde and Douala IXPs,” November 15, 2020,