Refer to the exhibit. Router E learned about the PIM RP (designated as 7.7.7.7) from four different
sources. Routers A and D advertised the 7.0.0.0 network via EIGRP. Routers B and C advertised
the 7.0.0.0 network via OSPF. Considering that all four Ethernet interfaces on router E could
potentially lead back to the PIM-RP, when router E receives the first multicast packet down the
shared tree, which incoming interface will be used to successfully pass the RPF check?
A.
E0
B.
E1
C.
E2
D.
E3
E.
None of these interfaces will be used to successfully pass the RPF check.
F.
All of these interfaces would successfully pass the RPF check.
Explanation:
PIM will use the neighbor with the highest IP. E0 and E3 is taken in to account as EIGRP has
lower AD the OSPF, if both E0 and E3 cost are the same next there is rule that “When faced with
multiple equal cost paths to a source, IP multicast chooses the interface that has a Protocol
Independent Multicast (PIM) neighbor with the highest IP address as the incoming interface and
then sends prunes to PIM neighbors on the other links.”