Exterior Gateway Protokoll (EGP)

Exterior gateway protocols, or EGP, describe the class of routing protocols that exchange reachability information between different autonomous systems. They differ from interior gateway protocols such as OSPF, IS-IS or EIGRP, which operate within a single autonomous system. The focus of EGP is not on shortest paths but on reachability, routing policies and commercial agreements between network operators. Historically, EGP initially referred to a specific protocol used in the early internet, which has since been fully replaced. Today, the Border Gateway Protocol version 4 is the only exterior gateway protocol in practical use. EGP is relevant for internet service providers, data centres and organisations with their own AS number that connect to multiple providers and want to control traffic paths deliberately.