Multicast PIM Bidirectional mode traffic between sources and RPs

In bidirectional mode, sources can send traffic whenever they want, so if sources have something to send, they will be constantly sending it to the RP. However, when multicast packets arrive at the RP, they will be forwarded down the shared tree if there are receivers. If there are not, the traffic will be dropped.

Note that:

  • In PIM bidirectional mode the RP will never build an (S,G) entry and we only allow the (* ,G) entry for the shared tree.
  • PIM bidirectional does not use the PIM register / register-stop mechanism

That's why it's important to place the RP somewhere in "the middle" of your network as close as possible to sources and destinations.

Multicast bidirectional PIM advantages