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Re: RFC2821bis-01 Issue 12: IPv6 MX records and transitions (was: Re: IPv6)

2007-04-10 23:19:34

At 17:24 31-03-2007, John C Klensin wrote:
> How about a more radical approach, just forbid "IPv6 only"
> for the moment somewhere in section 5 ?  "IPv6 only" is IMO
> completely against the spirit of "if it can't receive mail
> it has no business to send mail".

Frank, that's too radical.

On the one hand, the "no substantive changes" rule, combined
with my impression that we don't have a lot of operational
experience with this, argues for just that solution.  On the
other, having to prohibit IPv6 (or IPv6-without-IPv4) in 2007
seems strange and very unfortunate.  RFC3974, which does derive
from operational experience, doesn't shed a lot of light on
this: a quick summary is that IPv4-only is ok, IPv6-only is ok,
but, for mixtures or unknown destinations, any IPv6 host had
better be running dual-stack with some IPv4 MX records.  That
document contains a few statements that I believe to be serious
errors (perhaps the reason it was published as an independent
submission with strong disclaimers), but it is at least a
thoughtful attempt to explore the problem.

Adding an IPv6 section to cover the above cases would mean a substantial change. I suggest against getting into that.

* Issue 11 was assigned to getting rid of the "A RR" references
in favor of something more general.  Those changes have already
been made in the working version of -02.

I didn't see the proposed change.  I suggest the following:

1. Replace "A RRs" in Section 2.3.5 and Section 5 with "address records".

2. Add the following note -

Note that where this document refers to "address records", it means A RR's or AAAA RR's.