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Re: Why is 0 UDP checksum not valid for IPv6?

Fred Baker <fredbaker.ietf@gmail.com> Thu, 05 January 2017 16:10 UTC

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Subject: Re: Why is 0 UDP checksum not valid for IPv6?
From: Fred Baker <fredbaker.ietf@gmail.com>
In-Reply-To: <CANFmOtk9=Zz-QXkvfYbduxKJ3cuOnWXr2yhwrQoxCNLC09C3aA@mail.gmail.com>
Date: Thu, 05 Jan 2017 08:10:13 -0800
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To: Naveen Kottapalli <naveen.sarma@gmail.com>
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> On Jan 5, 2017, at 2:07 AM, Naveen Kottapalli <naveen.sarma@gmail.com> wrote:
> 
> I see those two RFCs talk mainly about the usage of UDP in tunneled protocols, but couldn't find why it is mandated for a normal plain IPv6 packet carrying a UDP payload with a DNS query or a response.

The primary difference that triggered this is that whereas IPv4 has a header checksum, IPv6 does not, and there have been anecdotal reports of checksum errors being found in IPv4 packets in the wild. The IPv6 designers, mid-1990's, felt that not having a checksum AT ALL left room for concern, and leaving it to the application was too loose a rule.

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