The Choice: IPv4 Exhaustion or Transition to IPv6

Stephen Sprunk stephen at
Thu Jun 28 22:55:18 UTC 2007

Thus spake "Iljitsch van Beijnum" <iljitsch at>
> How about this: when the OS only has an IPv6 address, and an  application 
> wants to talk to an IPv4-only destination, automatically  proxy the TCP 
> session through an HTTPS proxy. This catches
> anything that uses TCP and doesn't need to know its own IPv4
> address (hard to know if you don't have one) which would be
> upwards of 95% of all protocols in widespread use. So we only
> have to fix that other 5%.

If you're going to go that route, you might as well just deploy a v6-to-v4 
NAT device.  It'll break all the same protocols (though you could add ALG 
code for popular ones if desired) and, for those that won't, doesn't require 
any end host or application knowledge of what's going on.

I've bounced around some ideas privately on how such devices would work, 
probably have it defined well enough now to make a draft, and even managed 
to come up with a snappy backronym for it, but the IETF does not appear to 
be interested in any v6 transition model that doesn't require dual-stacking 
every single existing host on the Internet before the first v6-only host 
appears -- and certainly not one that's an adaptation of that evil NAT 


Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov 

More information about the NANOG mailing list