v6 already is backwards compatible. Pretty much every form of backwards compatibility that is possible with v4 is available in v6. The problem is that v4 isn't

v6 already is backwards compatible. Pretty much every form of backwards compatibility that is possible with v4 is available in v6. The problem is that v4 isn't forwards compatible with larger address spaces, and that's a problem that any protocol with >32-bit addresses faces, because it's a problem with the design of v4, not the design of the new protocol. Replacing v6 will not help. > the lack of NAT is really an anti-feature. v6 doesn't lack NAT -- what it lacks is any sane reason to use NAT. That's a good thing.