Dell Networking 7048 Configuration Manual page 1164

Figure 42-5. PIM-SM SPT—Part 2
• Finally, special (S, G) RP-bit Prune messages are sent up the Shared Tree to
prune off this (S, G) traffic from the Shared Tree.
If this were not done, (S, G) traffic would continue flowing down the
Shared Tree resulting in duplicate (S, G) packets arriving at the receiver.
1164
Managing IPv4 and IPv6 Multicast