IGMP communicates in three types of messages:

• Report (Join): A host sends an unsolicited message to the upstream multicast router signaling that it wants to become a member of a specific multicast group.
• Leave Group (Leave): A host in a multicast group sends a message to the upstream multicast router signaling that it is leaving a multicast group.
• Query: The multicast router sends a message to the local router to determine which groups have members on the attached network, or to determine if a specific group has members on the attached network.