If more than 1 router in a LAN segment, an IGMP querier election takes place (election in the 224.0.0.1 multicast address).If there are none, the router removes the IGMP state for that group. When the leave group message is received by the router, it follows with a specific membership query to the group multicast address to determine whether there are any receivers interested in the group remaining in the subnet.When a receiver wants to leave a group, if it was the last receiver to respond to a query, it sends a leave group message to the all-routers group address 224.0.0.2.When the timer expires, receivers send membership reports for each group they belong to. In response to this query, receivers set an internal random timer between 0 and 10s (which can change if the max response time is using a non-default value).The router starts periodically sending general membership query messages (max response time field = 10s by default) into the subnet, to the all-hosts group address 224.0.0.1, to see whether any members are in the attached subnet.

When the local router starts receiving the multicast stream, it forwards it downstream to the subnet where the receiver that requested it resides.The local router sends this request upstream toward the source using a PIM join message.When a receiver wants to receive a multicast stream, it sends an unsolicited membership report ( IGMP join) to the local router for the group it wants to join (for example, 239.1.1.1).If the router does not have IGMP enabled on the interface, the request is ignored. When a receiver wants to receive multicast traffic from a source, it sends an IGMP join to its router.Must be supported by receivers and the router interfaces facing the receivers.Protocol that receivers use to join multicast groups and start receiving traffic from those groups.Internet Group Management Protocol (IGMP) A LAN segment can have multiple streams, and a receiver knows which traffic to send to the CPU for processing based on the MAC address assigned to the multicast traffic. Limited Scope Addresses (equivalent вЂњRFC1918вЂќ)Д®very multicast group address (IP address) is mapped to a special MAC address that allows Ethernet interfaces to identify multicast packets to a specific group. The IANA assigned the IP Class D address space 224.0.0.0/4 for multicast addressing: range from 224.0.0.0 to 239.255.255.255.

Multicast mac address converter