RE: I-D Action:draft-denis-v6ops-nat-addrsel-00.txt

[Dave Thaler <dthaler@windows.microsoft.com>]

I just read this draft and have the same view as Brian.
The current behavior is by design.

-Dave

> -----Original Message-----
> From: owner-v6ops@ops.ietf.org [mailto:owner-v6ops@ops.ietf.org] On
> Behalf Of Brian E Carpenter
> Sent: Friday, March 13, 2009 5:03 PM
> To: remi.denis-courmont@nokia.com
> Cc: IPv6 Operations
> Subject: Re: I-D Action:draft-denis-v6ops-nat-addrsel-00.txt
>
> Remi,
>
> I am not sure about this statement in your draft:
>
> >    Thus, the transitional (IPv6) address will be used instead of the
> >    native (IPv4) address, even though that should have been avoided.
>
> As I recall, the intention was always that IPv6 should be preferred
> to IPv4, when both are available. The statement you quote earlier
>
> >    [RFC3484] states that "the use of transitional addresses when
> native
> >    addresses are available [should be avoided]".
>
> was in my memory intended to refer to IPv6 versus IPv6, and not to
> IPv6 versus IPv4.
>
> On that view, the current behaviour is not a mistake. The mistake may
> be elsewhere: a black hole in the transitional IPv6 connectivity.
>
> You suggest:
>
> >    Several operating system vendors appear to work around this issue
> by
> >    assigning a global scope to IPv4 address.  Thus, rule 2 is no
> longer
> >    discriminating against the IPv4 address pair.
>
> True, but that is against the intention of discriminating in favour
> of IPv6. So while some vendors may have chosen this approach, it isn't
> what we wanted.
>
> I don't see why we'd fix an operational problem of black holes
> by discriminating in favour of IPv4 NAT. That would just serve to
> reduce the incentive to fix the black holes.
>
> > 6.  IPv6 Address Translation
> >
> >    The implications of IPv6 Address Translation and protocol
> translation
> >    are left beyond the scope of this document.  However, it can only
> be
> >    recommended that RFC3484 be taken into account when designing such
> >    translation systems.
>
> Since ULAs are defined to have global scope, I think there will
> be no problem.
>
>      Brian
>