DHCPv6 defines class based allocation of IA_NA and IA_TA IPv6 addresses. This document extends DHCPv6 prefix delegation with class based prefix allocation. It defines a new prefix class option to classify a prefix. It defines the behavior of a DHCPv6 client requesting a prefix to include the class of the prefix to be allocated and the DHCPv6 server behavior to select and offer a prefix from a given class. It discusses how IA_NA can be requested and assigned from a specific prefix class.