August 30th 2020: Analysis of CenturyLink/Level(3) outage

This post details how Cloudflare's diverse network of providers and automated systems successfully rerouted traffic around a significant CenturyLink/Level(3) outage, minimizing customer impact. It highlights the challenges posed by single-homed connectivity and BGP route withdrawal issues, and speculates on the root cause being a Flowspec rule impacting BGP announcements, drawing parallels to Cloudflare's own past Flowspec-induced outage. The post underscores the importance of robust network resilience and the complexities of internet routing protocols.