In IPv6-only provider networks@ transporting IPv4 packets encapsulated in IPv6 is a common solution to the problem of IPv4 service continuity. A number of differing functional approaches have been developed for this@ each having their own specific characteristics. As these approaches share a similar functional architecture and use the same data plane mechanisms@ this memo specifies a DHCPv6 option@ whereby a single instance of Customer Premises Equipment (CPE) can interwork with all of the standardized and proposed approaches to providing encapsulated IPv4-in-IPv6 services by providing a prioritization mechanism