BGP
Border Gateway Protocol — the path-vector protocol that routes traffic between autonomous systems on the internet.
Border Gateway Protocol (BGP) is the Exterior Gateway Protocol (EGP) that exchanges routing information between autonomous systems (ASes) — the independently administered networks that make up the internet. Unlike interior protocols such as OSPF or EIGRP, which optimize for shortest path within one organization, BGP is a path-vector protocol that selects routes using policy attributes: AS-path length, origin type, local preference, and MED. It runs over TCP port 179 with manually configured peers. eBGP connects separate ASes, while iBGP carries those routes within an AS. Recognize BGP as internet-scale routing, not a typical enterprise LAN protocol.
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