In order to make optimal use of network bandwidth in a communication 1->n I need to use multicast. In an on-premise datacenter with switch having IGMP snooping, the advantage of multicast is obvious. However, in IaaS like AWS this is not obvious as we are abstracted from the HW infrastructure. The problem comes when you need to transmit around 400 Mbps to more than one EC2 instances that may be hosted in any physical server. So this why I'm asking whether AWS supports multicast and IGMP snooping.
Historically, AWS VPCs have not supported multicast.
The AWS engineers have recently developed a proof-of-concept multicast overlay, that has support for IGMP snooping.
See Overlay Multicast in Amazon Virtual Private Cloud
This is only proof-of-concept and is not yet fully supported.