Which devices must run PIM and IGMP when enabling SD‑WAN multicast?

For SD-WAN multicast, Protocol Independent Multicast (PIM) and Internet Group Management Protocol (IGMP) are essential on branch devices with multicast receivers. IGMP runs on the receiver-side LAN to allow hosts to signal their interest in joining a multicast group to the local router. PIM then runs on the router to build and maintain the multicast distribution tree, ensuring multicast traffic reaches those interested receivers. Datacenter replicator devices handle the replication of multicast streams but don't necessarily run PIM/IGMP themselves for receiver signaling. Datacenter devices with multicast sources originate the traffic, but PIM/IGMP are primarily for distribution to receivers. Branch devices with unicast traffic do not require PIM/IGMP as these protocols are specific to multicast communication.