Unicast RPF Behavior with a Default Route

If you configure a default route that uses an interface configured with unicast RPF, unicast RPF behaves as follows:

• Strict mode—If no corresponding route is found in the routing table, the packet is accepted. A packet is not accepted when:

• The packet has a source address that matches a prefix in the routing table.
• The interface does not expect to receive a packet with this source address prefix.

• Loose mode—All packets are automatically accepted. For this reason, we recommend that you not configure unicast RPF loose mode on interfaces that the default route uses.