[arin-ppml] The non-deployment of IPv6

Fred Baker fred at cisco.com
Mon Dec 7 01:19:41 EST 2009

On Dec 7, 2009, at 12:11 PM, Michel Py wrote:

> I would entertain that IPv4+ (which would be a backwards-compatible  
> IPv4
> with the only difference being an extended address space) would be  
> much
> more popular as a solution if it was on the table.

It would make a lot of sense. How, precisely, would you achieve that?  
Recall that the problem there isn't a failure in the design of IPv6;  
it's that IPv4 was not designed to have an extensible address. Roughly  
translated into the King's English, that means "you can't get there  
from here in a reliable fashion."

The obvious solution would be to put a source and destination AS  
number in options in the IPv4 packet, and in the presence of such a  
thing route to the remote AS before attempting to interpret the  
address. That's essentially what Jim Fleming proposed in his IPv8  
model, but he did so in a non-backward compatible way. The question  
I'll ask is how one proposes to actually deploy this in a backward  
compatible fashion. Think "Windows 95" and all that.

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