Re: [BEHAVE] Questionon embedded address format in draft-baker-behave-v4v6-framework-02

["Dan Wing" <[e-mail]>]

> -----Original Message-----
> From: [e-mail] 
> [mailto:[e-mail]] On Behalf Of Iljitsch van Beijnum
> Sent: Friday, April 24, 2009 2:36 PM
> To: Rémi Després
> Cc: Behave WG
> Subject: Re: [BEHAVE] Questionon embedded address format in 
> draft-baker-behave-v4v6-framework-02
> 
> On 24 apr 2009, at 17:06, Rémi Després wrote:
> 
> >> i don't know if i want to go there, not at least until we 
> have the  
> >> WK prefix defined.
> 
> > IMHO, this remark is by itself an INCENTIVE to have a WKP asap. As  
> > soon there is one defined, DynDNS clients of IPv4-only servers can  
> > be upgraded to produce synthetic AAAAs and send them to 
> > existing DNS  
> > servers. The end result is that these servers become immediately  
> > accessible by IPv6-only clients whose NAT64s are configured with  
> > this prefix.
> 
> So you want to create synthetic AAAA records at the source (the  
> authoritative DNS server) and trust that there wil be a translator  
> somewhere that will provide connectivity for those AAAA addresses to  
> IPv6 hosts.
> 
> This is not a good idea. The translators aren't out there today, and  
> it's unlikely they're going to be universal any time soon.
> 
> And even if every IPv6 host were served by a translator, this 
> would be  
> problematic because now dual stack hosts will first try to 
> connect to  
> the synthetic AAAA address and only then to the real A address.
> 
> If people want to make their v4-only services available to IPv6-only  
> clients, what they should do is run their own translator locally (or  
> arrange to be served by someone else's translator) using global  
> unicast IPv6 addresses. Then the entire IPv6 internet will be 
> able to connect to those services through that translator and 
> there won't bre any problems.

That falls into the "well-known prefix causes harm" category.

I recall that one of the presentations at the Google IPv6 
conference showed there were a lot of Teredo and 6to4
prefixes advertised in DNS.  If IANA assigns a well known 
prefix for 6/4 translation, we should expect some people
will stick that prefix into their DNS records.  Perhaps
out of incompetence, perhaps while debugging or learning, 
or perhaps because 'it works fine for my site that way'.

-d