Unicast RPF and Default Routes

When the active route cannot be chosen from the routes in a routing table, the router chooses a default route. A default route is equivalent to an IP address of 0.0.0.0/0. If you configure a default route, and you configure unicast RPF on an interface that the default route uses, unicast RPF behaves differently than it does otherwise. For information about configuring default routes, see the JUNOS Internet Software Configuration Guide: Routing and Routing Protocols. The following sections describe how unicast RPF behaves when a default route uses an interface and when a default route does not use an interface:

• Unicast RPF Behavior with a Default Route
• Unicast RPF Behavior without a Default Route

To determine whether the default route uses an interface, enter the show route command:

user@host> show route destination-address

destination-address is the next-hop address of the configured default route. The default route uses the interfaces shown in the output of the show route command.