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Re: [tsvwg] Alternative version of the UDP FRAG option

Joe Touch <touch@strayalpha.com> Tue, 12 March 2019 22:40 UTC

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Date: Tue, 12 Mar 2019 15:40:04 -0700
From: Joe Touch <touch@strayalpha.com>
To: Raffaele Zullo <raffaele@erg.abdn.ac.uk>
Cc: "C. M. Heard" <heard@pobox.com>, tsvwg <tsvwg@ietf.org>
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Subject: Re: [tsvwg] Alternative version of the UDP FRAG option
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I'm still not following the need for this alternative. 

FRAG+LITE works fine - even through broken middleboxes with the checksum
bug - if used with CS=0, which is how it ought to be used. The trailing
checksum in the last fragment is over the reassembled total (or not if
also zero) and there's no utility in checksumming the fragments
themselves. 

This still allows the UDP options of the reassembled packet to use OCS,
regardless of the reassembly checksum. 

So what's missing and why is this alternate needed? 

Joe

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