Le 5 août 09 à 16:09, Iljitsch van Beijnum a écrit :
On 4 aug 2009, at 15:27, Rémi Després wrote:
That's pointless, because the IPv6 spec, against which
implementations have been heavily tested, reject such packets.
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.
Although actual IPv6 packets flowing over the internet aren't as
numerous as their IPv4 counterparts and at least "legacy" IPv6
stuff can't be as old as the oldest IPv4 stuff, we still have a
very large installed IPv6 base out there that isn't going to adapt
to modifying standards at the drop of a hat.
Never thought they were to adapt this way.
If you send UDP packets with 0 checksums to IPv6 hosts, expect many
of them to reject those packets for a very long time, at the very
least 5 years.
Too bad for these "many", but there is nothing vital here anyway.
Besides, if it takes 5 years to update IPv6 stacks; it's likely that
the coexistence period will last much longer.
Then, preventing blackholes in v4 to v6 translation will serve its
purpose for quite some time.
Is progress from what is implemented today a taboo?
(I hope not.)
It's not taboo, just very hard. Apple and Microsoft aren't
particularly quick with building in updates to the network stack,
and after they've done that, it can take a long time for holdouts
to upgrade. This is much harder than updating applications from
competing vendors running in user space.
If we would only work on easy things, we would miss many useful
opportunities, right?
But nobody is stopping you from coming up with a new UDP-like
encapsulation that doesn't have a checksum.
You are the father of this idea and, as far as I am concerned, should
remain so.
My point is about translated UDP in general, not focused on to tunnels.
RD
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