MAC Address-Based Multicast Group

The L2 multicast forwarding table (built using IGMPV2/V1 reports) consists of the IP Multicast group MAC address. For IPv4 multicast groups, 16 IP multicast group addresses map to the same multicast MAC address. For example, 224.1.1.1 and 225.1.1.1 map to the MAC address 01:00:5E:01:01:01, and IP addresses in the range [224-239].3.3.3 map to 01:00:5E:03:03:03. As a result, if a host requests 225.1.1.1 using IGMPv2 or IGMPv1, then it might receive multicast traffic of group 226.1.1.1 as well.