The internet breaks down into hundreds of thousands of networks. Big firms like Facebook have their own larger networks – known as autonomous systems. When you want to visit Facebook (or Instagram or WhatsApp), the back-end system that allows computers to connect with their network uses the Border Gateway Protocol (BGP) – a kind of postal service for the internet. In order to direct people to the websites they want to visit, BGP looks at all of the available paths that data could travel and picks the best route.
On Monday Facebook suddenly stopped providing the information the system needed to function. It meant nobody’s computers had any way of connecting to Facebook or its other sites.
Around six hours after Facebook, WhatsApp and Instagram went down, service started coming back online, though coverage was still spotty. Concerning the outage, Facebook VP of infrastructure Santosh Janardhan said in a statement Tuesday morning that it wanted to “make clear” there was “no malicious activity,” The fact that Facebook, Instagram, and WhatsApp all experienced significant issues for around six hours was a major event for many users.
“Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication. This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt,” Janardhan said.