http://www.rfc-editor.org/rfc/rfc5454.txt
RFC 5454: Dual-Stack Mobile IPv4, G. Tsirtsis, V. Park, H. Soliman2009-03-01T23:00:00-00:00This specification provides IPv6 extensions to the Mobile IPv4 protocol. The extensions allow a dual-stack node to use IPv4 and IPv6 home addresses as well as to move between IPv4 and dual stack network infrastructures. [STANDARDS-TRACK]