What is BGP ?

BGP, or Border Gateway Protocol, is a standardized exterior gateway protocol used to exchange routing and reachability information between autonomous systems (AS) on the internet.

Think of it as the internet’s GPS, guiding data packets to their destinations across different networks.

Each autonomous system—think of these as individual networks like ISPs, universities, or large companies—has its own set of IP addresses and routing policies. BGP enables these systems to share information about the best paths for data to travel, ensuring packets find their way efficiently across the global internet.

How BGP functions?

•  Routing Decisions: BGP routers maintain a table of paths (or routes) to different network destinations. They use attributes like AS paths, next-hop addresses, and policies to decide the best route.

•  Scalability: BGP is designed to handle the internet’s massive scale, managing thousands of routes and adapting to network changes like outages or new connections.

•  Types: There’s eBGP (external BGP) for routing between different autonomous systems and iBGP (internal BGP) for routing within a single AS.

For example, when you visit a website, BGP helps your data hop from your ISP’s network to the website’s server, potentially crossing multiple ASes along the way.

BGP is critical but not flawless. Misconfigurations or malicious attacks (like BGP hijacking) can reroute traffic, causing outages or security issues. It’s a complex protocol, but it’s the backbone of internet connectivity, ensuring networks can talk to each other globally.