Comment by vlovich123

By definition you’re trying to retain back compat. So you have a 4.4 source IP address. You try to establish a TCP connection to a legacy IPv4 website that isn’t 4.4 aware. What address is that website sending the response back to? Even if it is 4.4 aware, how do you guarantee it’s taking a path back through 4.4 aware servers? The whole point of adding an option header is to allow unmolested transit through existing IP stacks. If you’re saying you’re routing around them, then you’ve bifurcated the networks and you’re back to IPv6.