BGP (Basics)
BGP is the internet-scale routing protocol used between autonomous systems.
Updated: 2026-03-05
Definition
BGP (Border Gateway Protocol) is a path-vector routing protocol used to exchange routes between autonomous systems.
It’s widely used by ISPs and large networks; internally, some enterprises use iBGP for scale.
Key points
- AS-based routing (ASN)
- Path-vector with attributes
- Used for internet routing and multi-homing
Common mistakes
- Treating BGP like IGPs (OSPF/EIGRP) with simple metrics.
- Not understanding iBGP vs eBGP basics.
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