O recurso é chamado de enhanced-ipv4 ou EnIP, dê uma olhada em este documento (IPv4 com espaço de endereços de 64 bits, janeiro de 2015):
Enhanced IP (EnIP) was designed to minimize impact on core and border routers. ... EnIP packets carry additional address bits and state in an IP option, eliminating routing table updates like IPv6. EnIP supports end-to- end connectivity, a shortcoming of NAT, making it easier to implement mobile networks. Host renumbering is also not required in EnIP as has been the case with other 64-bit protocol proposals