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Configuring a PIM RPF Routing Table

By default, PIM uses inet.0 as its reverse-path-forwarding (RPF) routing table group. PIM uses an RPF routing table group to resolve its RPF neighbor for a particular multicast source address and to resolve the RPF neighbor for the RP address. PIM can optionally use inet.2 as its RPF routing table group. To do this, include the rib-groups statement at the [edit routing-options] hierarchy level. You must also include the export-rib statement because inet.0 cannot be the default table for exporting routes into another table with the import-rib statement. After configuring the routing table group, specify it as the value of the rib-group statement at the [edit protocols pim] hierarchy level:



[edit]
protocols {


pim {

rib-group group-name;
}


}

For more information on configuring RIB groups, see the JUNOS Routing Protocols Configuration Guide.

The following example defines the routing table group pim-rg and uses it to populate inet.2 for RPF checks:



[edit]
routing-options {


rib-groups {


pim-rg {
export-rib inet.0;
import-rib [ inet.0 inet.2 ];
}


}


}
protocols {


pim {
rib-group pim-rg;
}


}

For a list of the hierarchy levels at which you can include these statements, see the statement summary section for this statement.

Specifying additional import routing table groups or an export routing table group in the routing table group has no effect on PIM operation. PIM uses the first routing table group specified as an import routing table group.

PIM uses a single routing table group as its RPF routing table group. This ensures that the route with the longest matching prefix is chosen as the RPF route.

You can configure OSPF to populate inet.2 with OSPF routes that have regular IP next hops. This allows RPF to work properly even when MPLS is configured for traffic engineering, or when OSPF is configured to use “shortcuts” for local traffic.

You can also configure IS-IS to populate inet.2 with IS-IS routes that have regular IP next hops. This allows RPF to work properly even when MPLS is configured for traffic engineering, or when IS-IS is configured to use “shortcuts” for local traffic.

For more information on RPF tables and the OSPF and IS-IS routing protocols, see the JUNOS Routing Protocols Configuration Guide.

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