1982

In October 1982 Eric Rosen from BBN defines the so-called Exterior Gateway Protocol (EGP) in RFC 827 (Request for Comment). It is supposed to work as a interface protocol between different networks.
The Exterior Gateway Protocol should be used for exchanging information about availability between autonomous systems. The information of which networks are available at the moment is passed from network to network. Afterwards, this information is interpreted by the gateways of the autonomous system as routing information.

An EGP has three basic functions. Neighbours should be found. Therefore gateways of two separate networks communicate and determine, if they become EGP partners. Additionally the EGP detects the availability of its neighbours for which it verifies if certain earlier determined EGP-partners are still available or not. The main function is the detecting the availability of whole networks. Thus, all EGP-partners get a list of available networks in there neighbours’ autonomous system on request.