6.3.c [vi] DHCPv6 prefix delegation
When DHCPv6 server has the Prefix Delegation feature enabled, it acts as a delegating router. The delegating router automates the process of assigning prefixes to the requesting router (that is, the DHCP client). Once the server has delegated prefixes to the client, the interface that is connected to the local area network (LAN) of the requesting router has an IPv6 address using the received prefix block. The requesting router then announces this address in the Router Advertisement messages. The client routers (that is, the routers in the local network) can use the autoconfig option to pull the global IP address from the advertised Router Advertisement messages by the DHCP client.
Adam, Paul (2014-07-12). All-in-One CCIE V5 Written Exam Guide (Kindle Locations 5969-5972). . Kindle Edition.