On Monday, Nov. 6, users across the US could not access the internet due to a misconfiguration at an enterprise ISP (Internet Service Provider) known as Level 3. Level 3 is a company that provides Autonomous Systems (AS), which keep track of which IPs (Internet Protocols) are used by which networks. They use the Border Gateway Protocol (BGP) to establish and dictaye routes. For example, packets can route between networks A and B, but network A can also route packets to network C through network B, and so on. This is how internet service providers interoperate to let you browse the whole internet, not just the IP addresses on their own networks. The outage effected users of Comcast, Spectrum, Verizon, Cox, and other services across the country.
A spokesperson from Level 3 said in a statement to WIRED, “Our network experienced a service disruption affecting some customers with IP-based services, … the disruption was caused by a configuration error.” The ASes relayed incorrect IP information to ISPs which caused inefficient, or nonexistent routing to users, causing an outage. It’s like stoplights and signs. If there were no directions, the traffic would never get to where it wanted to go, and there would be jams and crashes. It’s the same in the data world, where packets to and from computers and phones across the internet communicate with web servers and each other. If the IP info is faulty or gone, the data would be lost and never get to where it is directed.