A technical problem was reported Sunday with CenturyLink, the US Internet service provider that keeps the sites up and running. The reason that seems to have led to this incident is the incorrect configuration in one of the centers data, which brought about a chaotic situation throughout Internet, as it led to a 3,5% drop in global web traffic. This technical issue has affected other ISPs, with a large number of companies experiencing connectivity issues.
The list of technology giants whose services "fell" with the technical problem of CenturyLink includes, among others: Amazon, Twitter, Microsoft (Xbox Live), Reddit, EA, Blizzard, Steam, Discord, Hulu, Duo Security, Imperva, NameCheap, OpenDNS.
Cloudflare, which was also heavily affected by the technical issue, said the CenturyLink incident led to a 3,5% drop in global web traffic, making it one of the largest online outages ever recorded.
The official CenturyLink website states that this issue came from the CenturyLink data center in Mississauga, a city near Ontario, Canada, and that the main cause of the incident appears to have been a false announcement. Flowspec. Flowspec is an extension of the BGP protocol that allows companies to use BGP paths to distribute rules firewall in their network. Flowspec announcements are commonly used to deal with serious security incidents, such as DDoS attacks or BGP attacks, enabling companies to change their entire network to mitigate attacks in just a few seconds.
According to Cloudflare, the incident is due to the fact that CenturyLink announced a new set of BGP routes and then accidentally deleted all routes through the incorrectly configured Flowspec rule. BGP routes inform each ISP of which IP address segments are available on network of. However, as CenturyLink's incorrect Flowspec command "dropped" some of the router within its network, some of them also started reporting incorrect BGP routes to other neighboring services Internet "Tier 1". This, in turn, destroyed other networks.
CenturyLink fixed the problem by telling all other Tier 1 ISPs to ignore any traffic coming from their network. Companies rarely make such decisions, as such a move leads to a complete loss of connectivity for all customers.
The company also had to reset all equipment and start with clean BGP routing tables, a process that took about seven hours to complete (from 12:13 UTC to 18:58 UTC), with the company's co-founder and CEO, Matthew Prince, to declare that this was a major global shutdown of the Internet.