At R2,
The router has no idea about RP and consequently invalidates the join received from R1
We configure the RP information on the remaining routers R2 and R3
Now the server is getting response from the client to the ping sent from the server to the multicast group
At R3 the mroute table shows
The RP information is correct and the RPF is set to R4 on the fa1/0 interface
RPF operation
Problem
The ping from the server stop working
Any idea?
As conclusion
In this post, we’ve checked the operation of PIM in sparse mode. The configuration of the RP is central to this mode of operation. From there all PIM routers build the forwarding tree toward the RP (using RPF rule to validate PIM exchanged messages). After this half of path is built, the second path is build from the server to the RP to join the first half of path already built. RPF is also in action to check that the source of the multicast traffic is also in the RPF path in terms of the unicast routing table.
