Compared to anycast, multicast is a well-known entity. It is used in the contemporary IPv4 Internet, mainly to transport video/audio data in real time (e.g., videoconferencing, TV/radio broadcast). Multicast in IPv6 is just an evolution of the mechanisms already in use.

There is a separate part of the IPv6 address space dedicated to multicast. It is identified by the prefix ff00::/8. So every multicast address starts with “ff” which makes them easy to distinguish. The internal structure of the remaining 120 bits is shown in Figure 3-4.

IPv6 multicast and multicast Addressing is discussed in more detail in Chapter 8.