Exterior Gateway Protocol (EGP)

Last Updated: September 19, 2018

Definition - What does Exterior Gateway Protocol (EGP) mean?

Exterior Gateway Protocol (EGP) is an obsolete routing protocol that was used for data exchange between neighboring gateway hosts in autonomous systems. EGP was frequently used by research institutes, universities, government agencies and private organizations, but was replaced by Border Gateway Protocol (BGP).

EGP is based on periodic message exchange polling for neighbor reachability and poll commands to request update responses. EGP is documented in RFC 904, which was published in April of 1984.

Exterior Gateway Protocol is also known as External Gateway Protocol.

Techopedia explains Exterior Gateway Protocol (EGP)

Prior to the introduction of BGP, Internet hosts used EGP for data table routing exchanges. The EGP routing table includes known routers, addresses, cost metrics and each optimal route selection path. The EGP model is built with finite event, action and transition automation.

EGP mechanisms are:

  • Acquire neighbors
  • Monitor neighbors
  • Exchange data as update messages

While Interior Gateway Protocols are used within a domain, EGP provides a way for neighboring routers in different domains to share information.

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