Anatomy of an Outage: What Took The Gambia Offline for Eight Hours
On the morning of January 4, 2022, The Gambia woke up to a complete loss of Internet connectivity. The outage, which began shortly after 01:00 UTC and lasted until around 09:45, was caused by a cascading pair of failures rather than a single catastrophic event. The Gambia's state-owned telecommunications provider, Gamtel, initially attributed the incident to "technical issues on the backup links," but the full picture was more nuanced.
BGP (Border Gateway Protocol) data from the country's autonomous systems shows a clear and dramatic spike in route withdrawal messages at 01:10 UTC. When a network's prefixes are withdrawn via BGP, it means the routers that constitute the global Internet can no longer find a path to deliver packets to those destinations. The Gambian ASNs (AS25250, AS37309, AS37503, AS37552, AS37524, AS37323, AS328488, AS328140) became effectively unreachable from the rest of the world.
How One Path Held the Whole Country
The Gambia's international connectivity is unusually concentrated. The primary link, the ACE (Africa Coast to Europe) submarine cable, was already out of service. This left The Gambia dependent on terrestrial backup links routed through Senegal via the provider Sonatel (AS8346).
Routing data confirms this dependency. By examining BGP paths for all Gambian networks, it becomes apparent that the path through Sonatel and Gamtel (AS25250) is the single conduit for the country's traffic. While Sonatel itself was unaffected and remained online, the specific interconnection between Sonatel and Gamtel was the choke point. This arrangement means that a failure in just one segment can isolate the entire country.
This pattern is not unique to The Gambia. The global Internet backbone relies on a complex web of submarine fiber-optic cables with landing points in multiple countries. A problem in one country or at one cable landing station can ripple outward, affecting entire regions that depend on those routes for transit.
The Root Cause: Not One Failure but Two
Gamtel's follow-up press release on January 5 revealed the underlying chain of events. The outage was not simply a matter of the primary link being down.
- Primary link failure: The ACE cable system, which serves 24 countries between Europe and Africa, had a fault that left The Gambia reliant solely on its terrestrial backup route through Senegal. A full repair was not expected until mid-January.
- Backup link failure: The terrestrial route itself was compromised by a faulty card at Toubakota, Senegal. This was a critical fault because both the Karang and Seleti points where connections cross from Senegal into The Gambia converge at that location. When the card failed, both the North and South links went down simultaneously, effectively severing the only remaining connection.
Gamtel's explanation that the complete isolation on the Sonatel link was due to this convergence point at Toubakota makes technical sense: what was meant to be redundancy was, in reality, a single point of failure.
The incident has prompted a response beyond routine repair. The Gambia Public Utilities Regulatory Authority acknowledged the severity of the problem, noting the impact on national security, the economy, and social activities. The Authority stated that operators, the Ministry of Information and Communications Infrastructure, and the government are exploring the possibility of securing a second fiber-optic cable backup to prevent a repeat of this kind of extended national outage. For a country whose Internet access is so dependent on a single path, diversifying connectivity infrastructure is the only durable defense against isolation.
