IPv6 multicast addresses are used for sending data packets to a group of nodes simultaneously. There are two types of IPv6 multicast addresses: well-known multicast addresses and solicited-node multicast addresses.
Well-known multicast addresses are reserved addresses and are used for specific purposes. For example, ff02::1 is the all-nodes multicast address and is used to send packets to all nodes on a network segment.
Solicited-node multicast addresses are generated automatically by the network interface card when an IPv6 address is assigned to it. This address is constructed by taking the prefix of the assigned IPv6 address and appending the 24-bit multicast organization identifier (MIO) 0xff02 to the prefix.
IPv6 multicast addresses are used by applications to communicate with multiple nodes simultaneously. To join a multicast group, a node sends an IGMP (Internet Group Management Protocol) join message to notify the network that it wants to receive packets sent to a particular multicast address. The router checks its multicast routing table and sends the packet to all nodes that have joined the group.
IPv6 multicast addresses have many advantages over IPv4 multicast addresses, such as a larger address space, easier address allocation, and improved efficiency in network transmission.
