Internet Group Management Protocol (IGMP)
The Internet Group Management Protocol (IGMP) protocol is associated with the process of multicasting. Multicasting is a mechanism by which groups of network devices can send and receive data between the members of the group at one time, rather than separately sending messages to each device in the group.
The IGMP protocol is used to register devices into a multicast group, as well as to discover what other devices on the network are members of the same multicast group. Common applications for multicasting include groups of routers on an internetwork and videoconferencing clients. IGMP operates at the network layer of the OSI model.