Installing and Administering Internet Services

Chapter 8 241

Conﬁguring gated

Overview

• EGP (External Gateway Protocol) is known as a “reachability”

protocol primarily because it permits a node on the NSFNET

backbone to exchange information with other backbone nodes about

whether a destination can be reached. Use EGP to communicate

routing information between autonomous systems.

• BGP (Border Gateway Protocol) is intended as a replacement for EGP.

BGP uses path attributes to select routes. One of the attributes that

BGP can pass is the sequence of autonomous systems that must be

traversed to reach a destination. gated supports BGP versions 2, 3,

and 4, as described in RFCs 1163 and 1267.

NOTE BGP is not currently supported on HP-UX systems.

gated also supports the Router Discovery Protocol (RDP), which is

neither an interior nor exterior gateway protocol. It is used to inform

hosts of the existence of routers they can send packets to. It is used

instead of, or in addition to, a statically conﬁgured default router. Router

Discovery is made up of two parts: a server part that runs on routers,

and a client part that runs on hosts.