Re: There Might Be An Alternative
How can we be sure routers will honor the option fields since there are already security concerns about the option fields: they already tend to block options around Record Routes (either for Loose or Strict Sources), so they may be leery about accepting other options. Next, how will the legacy hardware use the system if they aren't able to insert Option fields themselves? Sounds like a similar problem from a different angle. Furthermore, since the scheme requires the use of a new kind of edge router, why not just use the same location for some kind of proxy server for those instances where an IPv4-only device MUST talk to an IPv6-only device (as a proxy is the only practical approach to bridging the protocols) without using options that they may not be able to make?
In essence, using the option field seems to have incompatibility issues of its own that make it just look like IPv6 in another package.