Multicast PIM Prune Override

This topic is to discuss the following lesson:

Hi Rene,

Very nice article. I was curious about the value of the timer on R1 once it receives prune message from the R2



So R2 will keep receiving the multicast stream even though it does not have a receiver. I wonder if the switch(es) sitting in the middle of the Multiaccess segment can do something to avoid sending the multicast stream to R2 once it sends the PIM Prune msg.

Hello Muhmmad

That’s a good question. It would seem that something like IGMP snooping could be used in such a case to ensure unwanted multicast traffic doesn’t reach a router like that. Although Layer 2 switches are IGMP-aware and can deal with delivering multicast traffic only to hosts that want it, they are unable to act upon PIM messages such as PIM prune in the same way, to help in making such communication more efficient.

In such a case, a network designer should choose a better topology, such as ensuring that R2 and R3 are in different network segments.

I hope this has been helpful!