Re: There Might Be An Alternative
0) Thanks for your comment.
1) "legacy hardware which can't be expected to be retired or replaced anytime soon ... ": This is the first criterion when we started to formulate the EzIP scheme.
2) "there may be a need for it to cross the IPv6 network ": Yes, we want IP packets to be able to cross the Internet which does not need to be IPv6. Under the Dual-Stack configuration, we can view the Internet as based on IPv4.
3) "make this possible using nothing but IPv4": Yes, the facility has been in plain sight ever since the original RFC791 that defined IPv4. It has the Option word mechanism in the IP header that can carry any binary string (formed into 8-bit octets) as payload. So, existing Internet routers will not act upon the extension address information contained in the Option words.
4) The EzIP is not implemented into existing routers, but into an added "sphere" of new routers, called SPR (Semi-Public Router), inserted inline between an ER (Edge Router) and the premises it serves. So, the SPR is installed where the service is needed, not affecting the existing equipment.
Hope these clear up the concerns that you have.
Abe (2018-07-06 18:25)