The (conceptual) table listing PIM information for
candidate Rendezvous Points (RPs) for IP multicast groups.
When the local router is the BSR, this information is
obtained from received Candidate-RP-Advertisements. When
the local router is not the BSR, this information is
obtained from received RP-Set messages.
snPimEnable must be 'enabled' before this
table is read or writen.