Similar to an IPv4 DHCP client, a DHCPv6 client is authenticated at its Solicit message, where it can request one or more addresses or prefixes. The address and prefix types supported are IA_NA (Non-Temporary Address) through the Alc-IPv6-Address RADIUS attribute and IA_PD (Delegated Prefix) through the Delegated-IPv6-Prefix attribute. Contrary to the IPv4 case, the BNG always replies to a DHCPv6 request because the client may request more than one address or prefix simultaneously and not all of the requests may be honored.
The DHCPv6 protocol handling and Router Advertisement behavior are similar to the PPPoE RG case above, with the exception that for an IA_NA address, the entire /64 prefix containing the address is allocated to the client.
For SLAAC prefix assignment, authentication is triggered on router-solicit message. The SLAAC prefix can be assigned statically or dynamically. For a static SLAAC prefix, frame-ipv6-prefix, RADIUS attribute is used. For dynamic SLAAC prefix assignment from a local pool, Alc-slaac-ipv6-pool, RADIUS attribute is used.