Yes. but that is not related to this discussion as far as I understand it. He wants to send IPv4 traffic inside IPv6, which can be done locally without issue. E.g. we have GRE6 in use (GRE over IPv6) transporting 44.x.x.x IPv4 traffic between routers.  It is always possible to do that, but you need cooperating hosts at both ends. E.g. when you cannot get IP tunnel mesh working due to ISP or router restrictions. Rob