In PIM Sparse Mode after registering (S,G) and (*,G) in Rendezvous point How data traffic is forwarded from source to Receivers?

In this scenario if source want to recieve traffic from the server, if server is already having (S,G) entry the process will be as follows:-

1-User will send report message to the upstream router.

2-R5 will send a join for the group towards RP(R3).

3-When RP gets the join, it will forward that join to upstream RPF neighbor.

4-It means R3 to R2 to R1 , now R1 will start forwarding stream towards RP and RP forward it to R5 and then to user.

5-As for the first time stream will pass through RP and R5 will receive the stream, R5 will check its routing table as it is having better path to reach the source via R4.

(Check EIGRP metric in this case)

6-R5 will send a prune message towards RP and a join message towards R4 with SPT bit set and start recieving stream from R4.

It means in sparse mode also , traffic should not always pass through RP.It will take the shortest path.

You can also disable this feature by running command ip pim spt-threshold infinity.

In this case traffic will always pass through RP.