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.