IGMP message types

Different Types of IGMP messages

The main motive behind IGMP (Internet Group Management Protocol) is to allow hosts in a subnet to communicate to local multicast routers about their intention to receive traffic addressed to a multicast group. There are different types of messages used to communicate between a multicast router and a multicast client.

IGMP General Membership Query (MQ) messages : General Membership Query (MQ) messages are sent by local multicast routers to its connected subnets to identify the multicast groups which the multicast clients in the network are interested to subscribe. General Membership Query (MQ) messages are sent by multicast router to the computers on its subnet at link-local All systems multicast address 224.0.0.1.

IGMP Group-specific Multicast Query (MQ) messages : Group-specific Multicast Query (MQ) messages are sent to a specific multicast group address as the destination IPv4 address. Group-specific Multicast Query (MQ) messages are used to determine the members of a particular multicast group.

IGMP Group-and-source-specific Multicast Query (MQ) messages : Group-and-source-specific Multicast Query (MQ) messages are used by the multicast routers to find any computer is interested to receive messages from a multicast group with specific source list.

IGMP Membership Report messages : IGMP Membership Report messages are sent by multicast clients inside the subnet to the router to inform the intention to join a multicast group or in response to a Membership Query (MQ) message sent by the router.

IGMP Leave Group (LG) messages : Leave Group (LG) messages are sent by multicast clients to local multicast routers to inform that they are no longer interested in traffic from a particular group.

IGMP message Type numbers

Different types of IGMP messages are identified in IGMP header by following IGMP Type values