IGMP: Internet Group Management Protocol
- IGMP is automatically enabled when PIM enabled.
- IGMP enables the communication between multicast routers and their hosts.
- Multicast routers uses the IGMP to send ip packets to what multicast groups on what interfaces.
- Host Membership query:
- Routers use the queries to discover the presence of multicast group member on a subnet.
- general membership query is sent to the group address 0.0.0.0.
- group specific query is sent to the group address that is required.
- Host Membership Reports:
- Hosts replies to queries.