Description: The value of vRtrPimNgAFGenRpfLookupSequence specifies the sequence of route tables that PIM uses for finding a Reverse Path Forwarding(RPF) interface for a particular multicast route.

'mucastRouteTable' is the unicast route table to be used only by multicast protocols(PIM) which will contain routes submitted by multi-protocol BGP, ISIS and OSPF.

'ucastRouteTable' is the regular unicast route table which will contain routes submitted by all the unicast routing protocols. By default, only the 'ucastRouteTable' is looked up by PIM for calculating RPF interface towards the source or rendezvous point. However the operator can specify the following: a) Use unicast route table only b) Use multicast unicast route table only or c) Use both the route tables.

In case of (c), PIM will always lookup first in the 'mucastRouteTable' and if there is a route, it will use it. If PIM does not find a route in the first lookup, it will try to find it in the 'ucastRouteTable'.