Re: ocean: do not boil

[Senthil Sivakumar <ssenthil@cisco.com>]

On Fri, 27 Sep 2002 itojun@iijlab.net wrote:

> >Now the dual-stack problem: with NAT-PT, dual-stack will always be forced
> >to use a IPv6-mapped address (translation path) that the DNS-ALG
> >synthesized for a v4 destination. dual-stack could very well use IPv4 to
> >talk to the destination, but is forced to use IPv6+NAT-PT because of
> >DNS-ALG's current behavior. this is assuming dual-stack is sending AAAA
> >first, and then A; but not true for other cases.
>
> 	site -> outside:
> 	- if the site uses private IPv4 addrss and IPv4 NAT, it doesn't really
> 	  matter if we use NAT-PT or IPv4 NAT.

The ALG support on NAT vs NAT-PT would be the difference.

> 	within site
> 	- DNS-ALG needs to be clever when returning synthesized AAAA address
> 	  for NAT-PT.  for instance, DNS-ALG could do the following when asked
> 	  for AAAA of foo.example.com:
> 		query AAAA for foo.example.com - it's not there
> 		query A for foo.example.com - it should be there (X)
> 		if X is within the site, return empty answer section with
> 			NOERROR (indicate that foo.example.com does not have
> 			AAAA, and invite client to use IPv4)

How do you determine if X is within the site or outside?

Senthil
> 		if X is outside the site, return synthesized AAAA record
> 			for NAT-PT translation.
>
> itojun
>
>