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Facebook: a major outage

The major outage that hit Facebook was caused by a routing problem related to the BGP protocol

This 4 October 2021, an outage made Facebook, Messenger, Instagram, and WhatsApp inaccessible for 5 hours. While some may have mentioned the possibility of a cyberattack, the problem was actually related to the routers of Facebook’s data centres, precisely to a failure of the Border Gateway Protocol (BGP).

During a routine configuration update of these routers, a high number of route deletion BGP messages were sent in error. This influx of messages caused a chain reaction, which led to the disconnection from the Internet of all of Facebook’s services, including Instagram and WhatsApp.

The BGP protocol is at the heart of the deployment of the Internet worldwide. In particular, it allows the cooperation of different operators to route all Internet traffic to its destination, via the exchange of access paths.

This protocol dates from 1994 and remains fragile, despite its revision in 2006. Its vulnerability has already led to several major incidents, either due to errors or deliberate manipulation.

On 12 June 2015, for example, the operator Telekom Malaysia mistakenly announced a large number of erroneous routes, which were then picked up globally. This failure of the BGP protocol drove a significant amount of Internet traffic to the operator, causing slowdowns and disruptions that were felt on a global scale.

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