Networking Guide
Chapter 5, Configuring Internet Protocol (IP) routing

gated preferences and route selection

gated preferences and route selection

Preference is the value gated uses to order preference of routes from one protocol or peer over another. Preference can be set in the gated configuration files in several different configuration statements. Preference can be set based on one network interface over another, from one protocol over another, or from one remote gateway over another. Preference may not be used to control the selection of routes within an ``interior gateway protocol'' (igp), this is accomplished automatically by the protocol based on metric. Preference may be used to select routes from the same ``exterior gateway protocol'' (egp) learned from different peers or autonomous systems. Each route has only one preference value associated with it, even though preference can be set at many places in the configuration file. Simply, the last or most specific preference value set for a route is the value used.

The preference value is an arbitrarily assigned value used to determine the order of routes to the same destination in a single routing database. The active route is chosen by the lowest preference value.