TABLE OF CONTENTS IP multicasting is one of the key technologies for the next generation of the Internet. In fact, IPv6 basic features such as the Neighbor Discovery protocol actively and effectively use multicasting as shown in Chapter 5 of IPv6Core Protocols Implementation, "Neighbor Discovery and Stateless Address Autoconfiguration." Meantime, increasing network bandwidth makes applications such as video streaming more realistic, which then makes IP multicasting more important.
Although the basic notion of multicasting is common to both IPv4 and IPv6, IPv6 multicasting brings several new characteristics based on operational experiences gained from the IPv4 counterpart. For example, IPv6 explicitly limits the scope of a multicast address by using a fixed address field (see Chapter 2 of the Core Protocols book, "IPv6 Addressing Architecture"), whereas in IPv4 the scope was specified by means of TTL (Time To Live) of a multicast packet.
The notion of explicit multicast scoping (called administratively scoped multicast) was introduced in IPv4 multicasting subsequently. The IPv6 multicast scope can be regarded as a built-in extension of administrative scoping.
In addition, the wider address space of IPv6 eases multicast group management. As shown in Chapter 2 of the Core Protocols book, the IPv6 multicast address format allows users to allocate and manage a wide range of groups by themselves without fear of collisions. All of these points indicate multicasting is and will be more effective in IPv6.
This chapter discusses details about IPv6 multicasting, especially on multicast routing mechanisms. We first explain the basic...
