# Multicast Boundary Filtering **URL:** https://forum.networklessons.com/t/multicast-boundary-filtering/2781 **Category:** Lessons Discussion **Created:** [January 23, 2018, 12:40pm UTC](https://forum.networklessons.com/t/multicast-boundary-filtering/2781 "2018-01-23T12:40:06Z") **Posts on this page:** 1 **Showing post:** 3
### Author: ![e.m.nech](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/e.m.nech/32/2071_2.png) [@e.m.nech](https://forum.networklessons.com/u/e.m.nech) #### Post date: [January 31, 2020, 12:04am UTC](https://forum.networklessons.com/t/multicast-boundary-filtering/2781/3 "2020-01-31T00:04:22Z")
Good day! This topic makes me go deeper to multicast! And i’ll explain why) I could not understand why do we need 224.0.1.40 for R3 (permit rule in MULTICAST\_FILTER acl). R3 is a client (receiver) of MC groups and all that we need for receiving multicast on R3 it is just sending IGMP report (join) toward the R2 (we can forget about PIM), and R2 knows where RP is. Hours of labing I understood, the main reason why we need acl with 224.0.1.40 in MULTICAST\_FILTER acl is “ **R3 acts as PIM-DR** ” I think that we do not pass packets with dst ip 224.0.1.40 through R2 is not the main problem **in this topology!** (avoiding chicken-and-egg problem is important but …) I Just think that the one of central points of this topic is PIM DR R3 my thoughts: 1. IF Multicast client (receiver) was not the Cisco R3 (where PIM and IGMP coexist together), but just a real client PC (vlc player) then permit rule for 224.0.1.40 in MULTICAST\_FILTER acl does not really needed 2. IF R2 is PIM DR (ip pim dr-priority ..) then permit rule for 224.0.1.40 in MULTICAST\_FILTER acl does not really needed 3. if we use “ip pim passive” command on R3 then permit rule for 224.0.1.40 in MULTICAST\_FILTER acl does not really needed Just to make sure Are my thoughts in the right way or I miss smth? --- _[View the full topic](https://forum.networklessons.com/t/multicast-boundary-filtering/2781)._