Mapping IPv6 Multicast Addresses to Ethernet Addresses When sending IPv6 multicast packets on an Ethernet link, the corresponding destination MAC address is 33-33-mm-mm-mm-mm where mm-mm-mm-mm is a direct mapping of the last 32 bits of the IPv6 multicast address, as shown in Figure above
For example, a host with the Ethernet MAC address of 00-AA-00-3F-2A-1C (link-local address of FE80::2AA:FF:FE3F:2A1C) registers the following multicast MAC addresses with the Ethernet adapter:
The address of 33-33-00-00-00-01, which corresponds to the link-local scope all-nodes multicast address of FF02::1.
The address of 33-33-FF-3F-2A-1C, which corresponds to the solicited-node address of FF02::1:FF3F:2A1C. Remember that the solicited-node address is the prefix FF02::1:FF00:0/104 and the last 24-bits of the unicast IPv6 address.
Mapping of class D IP address into Ethernet Multicast Address
IANA has allotted 01:00:5e:00:00:00 through 01:00:5e:7f:ff:ff for multicast
Lower order 23 bits if gp id copied to ethernet address
Eg1: 188.8.131.52 (hex e0.80.40.20) maps to hex 01:00:5e:00:40:20
Eg2 : 184.108.40.206 (hex e0.00.40.20) also maps to hex 01:00:5e:00:40:20