Exterior Gateway Protocol (EGP)

The Exterior Gateway Protocol (EGP) was the first inter-AS communications method used with TCP/IP and is still in use today in some circumstances. Rather than allowing your AS border router to locate neighbors on its own, you tell it up front the IP addresses or fully qualified domain names of other AS border routers with which it will exchange routing information. After you do this, EGP takes over to acquire those neighbors.

When an EGP-based AS border router comes alive, it is considered to be in an Acquisition state (EGP has a number of designations called “states” that describe the AS border router’s status, where the terms often double as commands). The state can be different for each acquired neighbor at ...

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