Os switches de Camada 2 que não estão cientes das junções IGMP / PIM normalmente inundam o tráfego multicast; pontos de acesso wi-fi se comportam como uma espécie de switch Layer2.
De RFC 5110 - Visão geral da arquitetura de roteamento de difusão seletiva da Internet
2.0 Multicast Routing
... When multicast transmission arrives at the receiver's LAN, it is flooded to every Ethernet switch port unless flooding reduction such as IGMP snooping is employed (Section 2.7).
Em seguida, na Seção 2.7 ...
2.7. Restricting Multicast Flooding in the Link Layer
Multicast transmission in the link layer, for example Ethernet, typically includes some form of flooding the packets through a LAN. This causes unnecessary bandwidth usage and discarding unwanted frames on those nodes which did not want to receive the multicast transmission.