IPマルチキャスト
The IP multicast standard was designed to scale to multicast groups with many members. It works well when doing a distribution similar to broadcasting, but it has scalability problems to a large number of groups. Multicast routing protocols keep routing tables that record multicast group addresses with members. These tables might become large, that prompted alternative schemes to reduce the quantity of state information. IP Multicast protocols announce a source or maintain routes between routers. The cost of these protocols can be significant even then the size of each group is reduced.