Router>enable
Router#configure terminal
Router(config)#ipv6 dhcp pool poolname
Router(config-dhcp)#domain-name domain
Router(config-dhcp)#dns-server ipv6 address of DNS server
Router(config-dhcp)#prefix-delegation ipv6-prefix/prefix-length client-DUID [iaid] [lifetime]
Router(config-dhcp)#prefix-delegation pool poolname [lifetime {valid-lifetime | preferred-lifetime}]
Router(config-dhcp)#exit
Router(config)#interface type number
Router(config-if)#ipv6 dhcp server poolnam...