BGP Routing Explained
BGP routing is the mechanism by which autonomous systems (ASNs) exchange reachability information across the internet. Every time you visit a website, BGP routing determines the path your packets take through dozens of networks to reach the destination server.
Cómo Funciona
BGP routers maintain a table of network prefixes (routes) and their associated paths. When a BGP session is established between two peers, they exchange their routing tables. Each router then applies local policies to select the best path for each prefix. Key attributes include AS_PATH (list of ASNs traversed), LOCAL_PREF, MED, and NEXT_HOP. Route selection follows a deterministic order: highest LOCAL_PREF → shortest AS_PATH → lowest MED → prefer eBGP over iBGP → lowest router ID.
Por Qué Importa
BGP routing determines the performance, reliability, and security of internet traffic. Route leaks can cause traffic to traverse unexpected networks. BGP hijacks can redirect traffic maliciously. Understanding BGP routing helps diagnose slow connectivity, investigate outages, and implement proper network security with RPKI validation.
Problemas Comunes
- Route leaks exposing internal routes to the public internet
- BGP hijacking redirecting traffic through unauthorized ASNs
- Slow BGP convergence causing temporary connectivity loss
- Suboptimal path selection due to misconfigured LOCAL_PREF
- Missing or incorrect NEXT_HOP causing routing black holes