Re: [tsvwg] draft-ietf-udp-options issues from IETF 104

[Tom Herbert <[e-mail]>]

On Fri, Jul 12, 2019 at 12:40 PM Joe Touch <[e-mail]> wrote:
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> On 2019-07-12 12:10, Tom Herbert wrote:
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> "baked in" or not, it a bug according to the requirements as of RFC6936 - and it needs to be addressed.
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> What is the bug?
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> Intermediate devices Dropping UDP packets with zero checksums.
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> They have been doing this for years
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> It's been wrong for years...
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> and it is consistent with the
> Internet standard, i.e. RFC2460
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> Yes, but not since RFC6936 (granted, that should have updated 2460)...
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> and now RFC8200 are very clear that
> checksums are required for UDPv6.
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> It's also very clear that they are NOT always required, as per Sec 8.1.
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> RFC6935 is also clear that it's the
> responsibility of the tunnel protocols to deal with any
> incompatibility that the use of UDPv6 zero checksums creates:
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> "Tunnel protocols intending to use a zero UDP checksum need to ensure
> that they have defined a method for handling cases when a middlebox
> prevents the path between the tunnel ingress and egress from
> supporting transmission of datagrams with a zero UDP checksum.  This
> is especially important as middleboxes that conform to RFC 2460 are
> likely to discard datagrams with a zero UDP checksum."
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> That recognizes existing deployment *at that time*. It doesn't provide for continued ignorance of the change.
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> Further, middleboxes that conform to RFC 2460 shouldn't be modifying the headers anyway...
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And yet they do... have you ever heard of NAT?

In any case, I don't get the point of this coversation. We already
_have_ a working solution for the Internet. Non-zero UDP checksums
have long been accounted for and optimized. We have no users clamoring
to use zero UDP checksums. Turning up UDPv6 zero checksums is not a
leap forward any more than trying to make TCP checksums optional.

Tom