BGP

ELI5 - The Vibe Check

BGP is the protocol that lets the entire internet's independent networks tell each other 'here's how to reach me' and figure out the best path for your data to travel across companies and countries that have never met each other. It's less a single network and more thousands of networks constantly gossiping about routes. It's also famously fragile: one misconfigured router at an ISP has taken down huge chunks of the internet before.

Real Talk

BGP is the routing protocol that exchanges reachability information between autonomous systems (independently administered networks) on the internet, determining the path traffic takes between networks based on policy, path length, and other attributes rather than pure shortest-path metrics. It underlies anycast routing, multi-homed connectivity, and cloud provider peering, and BGP misconfigurations (route leaks or hijacks) are a recurring cause of major internet outages.

When You'll Hear This

"That outage was a BGP route leak, half of Cloudflare's anycast routes went to the wrong place." / "We're multi-homed with two ISPs and BGP handles the failover automatically."