Configure Route Preferences

Route preferences are used to select which route is installed in the forwarding table when several protocols calculate routes to the same destination. The route with the lowest preference value is selected. For more information about route preferences, see Route Preferences.

By default, Level 1 IS-IS internal routes have a preference value of 15, Level 2 IS-IS internal routes have a preference of 18, Level 1 IS-IS external routes have a preference of 160, and Level 2 external routes have a preference of 165. To change the preference values, include the preference statement (for internal routes) or the external-preference statement (for external routes) at the [edit protocols isis level level-number] hierarchy level (for routing instances, include the statement at the [edit routing-instances routing-instance-name protocols isis level level-number] hierarchy level):

[edit protocols isis level level-number]

external-preference preference; 

preference preference; 

The preference value can range from 0 through 255.