Re: A new transition plan, was: Re: the evilness of NAT-PT, was: chicago

On Jul 6, 2007, at 3:07 AM, Iljitsch van Beijnum wrote:

> > And from an architectural perspective, address translation is  
> > clearly a dead end. One of the reasons we argue against NATs is  
> > not that there aren't other major problems, it's that people  
> > haven't managed to get the message on NATs yet.
> Well, an iceberg looks very differently depending on whether you  
> look at it above water or below. The problem with NAT is like  
> almost all persisting problems: the bad consequences aren't felt in  
> the place where they're created.
It should be abundantly clear, being "Internet robust" is not a  
requirement set by the marketplace.  People want their multiplayer  
games and conferencing programs to "just work"!  A transition to full  
IPv6 will be perilous, as it is _not_ possible to drop IPv4 support  
in most environments.
Unfortunately, the NAT problem also represents a business  
opportunity.  This is true whether or not the solutions are condoned  
by a standards body.  In the case of IPv6, Teredo UDP IPv4 tunneling,  
Teredo servers, and PNRP (a name service to navigate Teredo  
topologies) represents an immediate solution.  A solution that  
introduces _more_ translations.
The ideals of end-to-end assume the "end" is "Internet robust."  With  
Teredo and PNRP, external services play a significant role.  Will the  
"end", in conjunction with extremely complex topology ever become  
"Internet robust"?
How will SMTP servers vet sources of inbound messages within an IPv6  
environment?  Virtually every grain of sand can obtain a "new" IPv6  
address.  An IPv6 address may traverse any number of translation  
points as well.
This complex topology spells the end of SMTP in its current form.   
Perhaps SMTP could depend upon SMTP Client names or change into a  
type of URI based notification process, where messages are held by an  
HTTP server.  The URI of the HTTP server might then replace reliance  
upon SMTP Client IP address reputation.  SMTP represents just one  
protocol heavily dependent upon IPv4.
As IPv4 becomes constrained, IPv4 based access control improves.   
Fully adopting IPv6 introduces another problem, IPv6 address access  
controls.
-Doug

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