Le 28 juil. 09 à 09:29, Francis Dupont a écrit :
=> I am strongly against changing all IPv6 implementations.
In this instance, the change is only a backward compatible additional
rule which is not a MUST.
There is no urgency to upgrade any host.
If an IPv6 host becomes capable to receive more UDP packets
translated from IPv4 (including those that are sent with checksum
zero), I don't see what harm it may cause to anyone else.
IMHO the simplest solution is to drop UDP packets with zero checksums
(as far as I know all IPv4 implementations use non-zero checksums
per default and some UDP applications, for instance DNS, work far
better with non-zero checksums. BTW it is an easy condition to check
in firewalls).
The point is just to improve connectivity where UDP zero checksums
ARE actually used, and this at no cost where they are not used.
To take in consideration your (useful) remark, the proposal could be
improved by replacing a SHOULD by a MAY:
- IPv6 hosts MAY accept UDP zero checksums (but of course MUST still
send non-zero UDP checksums).
- v4 to v6 translators MAY either compute UDP checksums when
receiving UDP zero checksums OR translate with the zero checksum
unchanged.
RD
Regards
francis.dup...@fdupont.fr
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