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BGP

eBGP vs iBGP: What's the Difference and When to Use Each

eBGP and iBGP look similar at a glance but behave very differently around TTL, next-hop, AS-path, and route advertisement. Treating them as the same protocol gets you in trouble fast; here are the rules.

J

Mar 28, 2026 4 min read

BGP

How BGP Works: Peers, Updates, and the Finite State Machine

BGP peering does not auto-discover. Every session is deliberately configured, runs over TCP port 179, and walks a strict finite state machine before a single route flows. The foundation you need before touching BGP config.

J

Mar 28, 2026 4 min read

BGP

What Is BGP? The Protocol That Runs the Internet

Every time you load a webpage, your traffic crosses networks owned by different organizations. BGP, the Border Gateway Protocol, is what stitches 75,000+ autonomous systems into a single working internet. Here is how, and why.

J

Mar 28, 2026 4 min read

BGP

BGP Route Filtering with Prefix Lists

Prefix lists are the preferred BGP filtering tool: faster than ACLs, easier to read, and built for matching networks with specific prefix lengths. Every production BGP deployment needs them on inbound and outbound.

J

Mar 28, 2026 5 min read

BGP

BGP Confederations: An Alternative to Route Reflectors

BGP confederations scale iBGP by dividing the AS into sub-ASes that speak confederation eBGP internally, while appearing as a single AS to the outside world. An alternative to route reflectors with tradeoffs you need to know.

J

Mar 28, 2026 4 min read

BGP

BGP Route Reflectors: Eliminating the Full Mesh

Ten routers need 45 iBGP sessions. Fifty need 1,225. Route reflectors break the iBGP split-horizon rule in a controlled way, and are the standard scaling tool for iBGP in enterprise and service provider networks.

J

Mar 28, 2026 4 min read