@fgutvar multicasting is very much dependent on your infrastructure. Multicast packets are normally blocked crossing your vlan routers this is by design. For multicasting across subnets there is typically a multicast router in place. This can be the same or different than your vlan router. The processing of unicast and multicast routing are different. Some standard IP routers have an igmp proxy service that will run. It functions much like a dhcp-relay or dhcp-helper service does, but the igmp proxy listens for multicast traffic and not dhcp traffic.