Unlike the PIM-DM protocol, PIM-SM does not congest the network with flooding messages; for that a Rendezvous Point (RP) is configured, which is the meeting point for recipients interested in information from the source; thus the origin of the data is constantly connected only to the RP so that the receivers do not flood the links close to the source.
Figure 9 shows the connection between the source and the n3 configured as RP for the implementation of the PIM-SM protocol.
Figure 10 shows that unlike the PIM-DM protocol, PIM-SM connects its interested receivers to the RP because as mentioned, this node becomes the meeting point of the network for group 1.
The bandwidth is directly affected regarding the implemented protocol for the proposed simulation; the PIM-DM protocol requires a higher percentage of bandwidth than PIM-SM due to the need to be sending messages of flooding and pruning to know the status of the network.
Shared tree can be constructed using a shared core tree: It requires the selection of a central router called "Rendezvous point" RP in PIM-SM  protocol and "Core" in CBT  protocol.
Several multicast routing protocols in the literature use Shared Core-Based Tree: Protocol Independent Multicasting-Sparse mode PIM-SM  and Core-Based Tree (CBT) .
Current implementation of PIM-SM  and CBT  protocols divides the tree construction problem into two sub problems: the first is center selection problem and the second is routing problem.
It is comparable to selecting the first source or the initiator of the multicast group, as proposed in PIM-SM  and CBT  protocols.
Protocol Independent Multicast--Sparse Mode (PIM-SM
): Protocol Specification.
In PIM-SM, even if a receiver has switched to source rooted trees for all active sources, the router state still needs to be maintained for RP rooted tree to enable packets to be received from a new source of the group.
PIM-SM  builds shared trees around one or more Rendezvous Points (RPs), (not necessarily the data source) from which data is multicast to group members.
If, for example, a certain multicast group comprises [R.sub.0] (the root of the tree), [R.sub.1], [R.sub.4,] [R.sub.9,] [R.sub.12,] and [R.sub.16,] then the overhead cost of setting up this group by PIM-SM is,