ent to multicast addresses. The scope is presented in a 4-bit value inside a multicast address, as illustrated in Figure 3.11, and hence has 16 distinct possibilities. Most of the values Deploying IPv6 in 3GPP Networks 8 bits 4 bits 4 bits 112 bits 1111 1111 flags scope Group ID Not yet assigned 1: Interface-Local scope R=1: Address embeds a 2: Link-Local scope Rendezvous Point address 4: Admin-Local scope R=0: Does not embed a 8: Organization-Local scope Rendezvous Point address E: Global scope P=1: Address is based on a network prefix P=0: Address is not based on a network prefix T=1: Transient address T=0: Permanent address Figure 3.11 Generic IPv6 multicast address format. Table 3.1 Subset of reserved IPv6 multicast addresses. 'X' in the multicast address indicates a variable scope address, as illustrated herein with the documentation address Multicast address Scope Description Reference ff01:0:0:0:0:0:0:1 Interface-Local All Nodes Address ff01:0:0:0:0:0:0:2 Interface-Local All Routers Address ff02:0:0:0:0:0:0:1 Link-Local All Nodes Address ff02:0:0:0:0:0:0:2 Link-Local All Routers Address ff02:0:0:0:0:0:0:16 Link-Local All MLDv2-capable Routers ff02::1:ff00:0000/104 Link-Local Solicited-Node Address ff02:0:0:0:0:2:ff00::/104 Link-Local Node Information Queries ff05:0:0:0:0:0:0:2 Site-Local All Routers Address ff05:0:0:0:0:0:1:3 Site-Local All DHCPv6 servers ff0x::db8:0:0/96 Variable Scope Documentation Addresses 8 bits 4 bits 4 bits 8 bits 8 bits 64 bits 32 bits 1111 1111 flags scope reserved network prefix group ID Figure 3.12 Unicast Prefix based IPv6 Multicast Address Format. Introduction to IPv6 are unassigned or reserved (scopes 0 and F). The allocated scopes, and related numerical values, are the following: Interface-Local (1), Link-Local (2), Admin-Local (4), Site-Local (5), Organization-Local (8), and Global (E) [4]. Table 3.1 illustrates some of the IANA allocated, reserved, and permanent, IPv6 multicast addresses, most of which are referenced in this book. It is important to realize IANA has alloca