> 3. Many networks will need to be dual-stack (IPv4 + IPv6) for many > years to come. dual stack requires an ipv4 address for every ipv6 address. the ipv6 wise folk who thought dual stack was *the* transition mechanism did not anticipate it would take decades; and hence run into the little problem that 2^32 is a wee bit smaller than 2^128. so we get widespread cgns. https://dl.acm.org/citation.cfm?id=2987474 randy