On Tuesday 04 August 2009 17:49:25 ext Rémi Després wrote:
> Le 4 août 09 à 16:30, Lars Eggert a écrit :
> > Hi,
> >
> > On 2009-8-4, at 16:27, Rémi Després wrote:
> >> You seem to have missed that the proposal includes a relaxation of
> >> the constraint that zero-checksum UDP datagrams MAY be accepted by
> >> hosts ion the future, just to avoid unnecessary black holes in case
> >> of v4 to v6 translations.
> >
> > isn't it a non-starter for a translation based *transition*
> > mechanism to depend on host changes?
>
> I don't think so, because it's never too late do do some good without
> doing any harm.
>
> IMHO, translators SHOULD forward zero-checksum datagrams RATHER THAN
> dropping them. No harm expected.

"No harm expected"? I find that generating scary-reading false positive in my 
system logs is harmful.

> IMHO also, hosts, at their next patch release, SHOULD silently accept
> zero-checksum IPv6 datagrams RATHER THAN silently dropping them. No
> harm expected.

That will cause silent software failures when running on a "too old" system. 
Silent failures are the most harmful kind of failures to me.

> By doing this, connectivity during the transition period will
> eventually be improved, possibly before translators are largely
> deployed.

No. By doing this, people will experience odd failure modes and weird error 
reports during the long transition period for IPv6 stacks to accept checksum-
less packets.

Harm very much expected.

-- 
Rémi Denis-Courmont
Nokia Devices R&D, Maemo Software, Helsinki

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