BGP Routing Explained: How the Internet's Navigation System Works

What is BGP?

The internet is not a single network — it is a collection of approximately 100,000 independent networks called Autonomous Systems (AS), each operated by an ISP, cloud provider, CDN, university, or large enterprise. BGP (Border Gateway Protocol) is the protocol these networks use to communicate routing information to each other: which IP address ranges each network can reach, and via which paths.

How a Packet Finds Its Way Across the Internet

When you access a website hosted in Mumbai from your laptop in Delhi, here is what happens:

1. Your ISP's router consults its BGP routing table to find the best path to the destination IP
2. The packet is forwarded through a series of AS hops — each hop brings it closer to the destination
3. At each AS boundary, BGP determines the next optimal hop based on AS path length, routing policies, and network relationships
4. The packet arrives at Power Down's network in Mumbai, then routes to the specific server

Autonomous System Numbers (ASNs)

Every network participating in BGP has a unique ASN (Autonomous System Number). Power Down Hosting peers with multiple upstream providers including Tata Communications, ensuring optimal routing and path redundancy. When one upstream has issues, BGP automatically reroutes traffic through alternate paths.

BGP and DDoS Mitigation

Cloudflare Magic Transit works by announcing your IP prefixes via BGP through Cloudflare's global network. When traffic is destined for your IPs, BGP routing tables globally point that traffic to Cloudflare's scrubbing centers first, where attacks are filtered before clean traffic reaches your servers.

FAQ

What is BGP hijacking?

BGP hijacking occurs when a malicious or misconfigured network announces incorrect routing for IP prefixes they do not own, redirecting traffic through their infrastructure. Route Origin Validation (ROV) and RPKI (Resource Public Key Infrastructure) are emerging standards to prevent this.