When an IGMP client connected to a switch port needs to receive multicast traffic from a specific group, it joins the group by sending an IGMP report (join request) to the network. When the client is ready to leave the multicast group, it sends a Leave Group message to the network and ceases to be a group member.

The Internet Group Message Protocol (IGMP) has many messages that are identified by a “type” field. Note that the original definition of IGMP in [RFC1112] divided this field into two 4-bit values, “version” and “type”….Type 0x11 – IGMP Membership Query.

A device can join a group by sending an IGMP “membership report” message to the group IP address. This packet is received by a multicast router on the segment, and the router does whatever is necessary to start forwarding the data stream to this device.

In (*,G) notation, the asterisk (*) is a wild card used to denote the state that applies to any source sending to group G. A multicast group can have more than one source. If two hosts are both acting as sources for the group 224.1.

ICMP stands for Internet Control Message Protocol. While IGMP stands for Internet Group Message Protocol. 2. ICMP has PING features.

The Internet Group Management Protocol (IGMP) is a communications protocol used by hosts and adjacent routers on IPv4 networks to establish multicast group memberships.

16 bits
IGMP Checksum. 16 bits. The checksum is the 16-bit one’s complement of the one’s complement sum of the 8-byte IGMP message. When the checksum is computed, the checksum field should first be cleared to 0.

IGMP can be used for one-to-many networking applications such as online streaming video and gaming, and allows more efficient use of resources when supporting these types of applications. IGMP is used on IPv4 networks.

IGMP snooping is a method that network switches use to identify multicast groups, which are groups of computers or devices that all receive the same network traffic. It enables switches to forward packets to the correct devices in their network.

IGMP Snooping Querier. The IGMP/MLD Snooping Querier is used to support a Layer 2 Multicast domain of snooping switches in the absence of a Multicast router. For example, where Multicast content is provided by a local server, but the router (if one exists) on that network does not support Multicast.

ICMP stands for Internet Control Message Protocol. While IGMP stands for Internet Group Message Protocol. ICMP can be operate between host to host or host to router or router to router. While IGMP can be used between client to multicast router.

IGMPv2 Membership Report messages (MR) includes the IPv4 Class D multicast address of the multicast group they want to join. IGMPv2 Membership Report (MR) message type number is 0x16. The point to note is that there is no separate Type of IGMPv2 Join message. An unsolicited Membership Report (MR) message is used as IGMPv2 Join message.

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.

It is the one’s complement of the one’s complement of the sum of IGMP message. The group address field is zero when sent and ignored when received in membership query message. In a membership report message, the group address field takes the IP host group address of the group being reported.

IGMP message Type numbers Message Type Type value number IGMP Membership Query (MQ) messages 0x11 IGMPv1 Membership Report (MR) messages 0x12 DVMRP 0x13 PIM version 1 0x14