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
Solicited node multicast address
It is formed by taking the lower order 24 bits of ( unicast or anycast )
When A node n1 which wants to find MAC address of node n2, it will send neighbor solicitation message with solicited multicast address to n2.
Node n2 will reply with neighbor advertisement message
A Node’s multi cast addresses
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: 126.96.36.199 (hex e0.80.40.20) maps to hex 01:00:5e:00:40:20
Eg2 : 188.8.131.52 (hex e0.00.40.20) also maps to hex 01:00:5e:00:40:20