4 reasons Facebook went down so badly last week
Packet switched networks were designed to withstand a nuclear attack. However, a series of mistakes triggered by a command that slipped through the auditing tools caused a global outage of Facebook on the 4th of Oct 2021, which is estimated to have temporarily cost 47 billion in market cap of the company, on top of a revenue loss between 60 and 100 million. More importantly, such events reveal how vulnerable our society has become to complex software systems. In this blog post we review the causes that triggered Facebook’s outage and the known facts about it. We will follow up in a second post with a plea for BGP change validation, a key technology to make BGP networks more resilient.