Re: [BEHAVE] UDP zero checksums and v4 to v6 translators

[Mohacsi Janos <mohacsi at niif.hu>]

On Tue, 4 Aug 2009, Rémi Després wrote:

> Le 4 ao?t 09 ? 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.
> Avoiding to drop them by computing payload checksums is another possible 
> behavior, at least for single fragment datagrams. But it implies to compute 
> payload checksums, which may be considered too expensive and opening a door 
> to DOS attacks.
>
> IMHO also, hosts, at their next patch release, SHOULD silently accept 
> zero-checksum IPv6 datagrams RATHER THAN silently dropping them. No harm 
> expected.

In your previous mail your state MAY instead of SHOULD. Or you are 
proposing submitting a draft? :
"Acceptance of zero checksum IPv6-UDP headers at end-host"

Best Regards,
		Janos Mohacsi