Unicast Rpf Behavior With A Default Route; Unicast Rpf Behavior Without A Default Route - Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual

To configure unicast RPF loose mode, include the
You can include this statement at the following hierarchy levels:
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 Routing Protocols
Configuration Guide.
To determine whether the default route uses an interface, enter the
command:
address
uses the interfaces shown in the output of the
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

If you configure a default route that uses an interface configured with unicast RPF,
unicast RPF behaves as follows:
Chapter 5: Configuring Protocol Family and Interface Address Properties
mode loose;
[edit interfaces interface-name unit logical-unit-number family (inet | inet6) rpf-check
<fail-filter filter-name>]
[edit logical-systems logical-system-name interfaces interface-name unit
logical-unit-number family (inet | inet6) rpf-check <fail-filter filter-name>]
user@host> show route address
is the next-hop address of the configured default route. The default route
Unicast RPF Behavior with a Default Route on page 217
Unicast RPF Behavior Without a Default Route on page 218
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.
Strict mode—The packet is accepted when either of the following is true:
The source address of the packet matches any of the routes (either default
or learned) that can be originated from the interface. Note that routes can
have multiple destinations associated with them; therefore, if one of the
destinations matches the incoming interface of the packet, the packet is
accepted.
The source address of the packet does not match any of the routes.
:
mode
show route
command.
show route
Configuring Unicast RPF
217