The IGMP communication protocol is used by the nodes and the adjacent routers on IP networks to interact and to establish ground rules for multicast communication and establish multicast group membership.

What is IGMP used for?

The Internet Group Management Protocol (IGMP) manages the membership of hosts and routing devices in multicast groups. IP hosts use IGMP to report their multicast group memberships to any immediately neighboring multicast routing devices.

Does Netflix use multicast?

Since multicast is so much more efficient than unicast, large companies like Netflix and Youtube must be using this to stream videos right? ... The only place where you might see multicast on the Internet is your local ISP. They typically use multicast for IPTV to deliver video to their own customers.