The reason the given route was placed in the (logical)
multicast Routing Information Base (RIB). A value of
unicast means that the route would normally be placed only
in the unicast RIB, but was placed in the multicast RIB
(instead or in addition) due to local configuration, such as
when running PIM over RIP. A value of multicast means that
the route was explicitly added to the multicast RIB by the
routing protocol, such as Multiprotocol BGP or DVMRP.