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<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif">Hi Cheol, Felix,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif">The efficiency of positive vs. negative claims is
<b>highly</b> dependent upon the behaviour of the underlying link. If a link has long periods of successful communication punctuated by brief (complete) fading events, then NACK may be better. If a link is more erratic, then the calculations become a bit harder
and are highly dependent on the ratio and duration of successful vs lost packets/frames.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif">In most “reliable” space links, fading is pretty intermittent (until your elevation reduces), so ACK/NACK should be pretty similar. I think Ka/optical might upset this balance
though… We’ll see.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-family:"Calibri",sans-serif">Jeremy</span><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> SIS-DTN <sis-dtn-bounces@mailman.ccsds.org>
<b>On Behalf Of </b>Felix Flentge via SIS-DTN<br>
<b>Sent:</b> Monday, April 4, 2022 12:08 PM<br>
<b>To:</b> </span><span lang="KO" style="font-size:11.0pt">구철회</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <chkoo@kari.re.kr><br>
<b>Cc:</b> sis-dtn@mailman.ccsds.org<br>
<b>Subject:</b> Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">Ah, yes, of course you are right.</span>
<br>
<br>
<span style="font-size:10.0pt;font-family:"Arial",sans-serif">We will look into the negative ACK as part of our LTPv2 prototyping activity.</span>
<br>
<br>
<span style="font-size:10.0pt;font-family:"Arial",sans-serif">Regards,</span> <br>
<span style="font-size:10.0pt;font-family:"Arial",sans-serif">Felix</span> <br>
<br>
<br>
<br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">From: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">"</span><span lang="KO" style="font-size:9.0pt">구철회</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">"
<<a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a>></span> <br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">To: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif"><<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>></span>
<br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Cc: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">"<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>></span>
<br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Date: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">04/04/2022 11:58</span>
<br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Subject: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">RE: Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation
and processing</span> <br>
<span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Sent by: </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif"><a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a></span>
<o:p></o:p></p>
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<p class="MsoNormal"><br>
<br>
<br>
Hi Felix, <br>
<br>
I think current LTP spec quite works well with negative claim also. Consider below reception claim according to the LTP spec but negative claim.
<br>
<br>
lower bound = 0 <br>
upper bound = 7000 <br>
negative reception claim count = 1 <br>
offset = 1000 <br>
length = 2000 <br>
<br>
it means a receiver is requesting block of segements which starts at 1000 and length is 2000, i.e., 1000 ~ 2999, for retransmission.
<br>
A sender can safely remove 2 blocks, i.e., 0 - 999 and 3000 - 7000. I think it is simpler, lower overhead and *importantly* easier to calculate (acutally no painful for localizing the target segment position).
<br>
<br>
Cheol <o:p></o:p></p>
<p style="margin-top:22.5pt"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0062E1">---------
</span></b><b><span lang="KO" style="font-size:9.0pt;color:#0062E1">원본</span></b><b><span lang="KO" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0062E1">
</span></b><b><span lang="KO" style="font-size:9.0pt;color:#0062E1">메일</span></b><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0062E1"> ---------</span></b><o:p></o:p></p>
<p class="MsoNormal"><br>
<b><span lang="KO" style="font-size:9.0pt">보낸사람</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> : <<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>><b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">받는사람</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> : "</span><span lang="KO" style="font-size:9.0pt">구철회</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">" <<a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a>><b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">참조</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> : "<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">받은날짜</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> : 2022-04-04 (</span><span lang="KO" style="font-size:9.0pt">월</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">)
17:40:24<b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">제목</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> : Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing</span>
<br>
<span style="font-size:10.0pt;font-family:"Arial",sans-serif">Hi Cheol,</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">
<br>
</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
interesting question. One thing I can think of is that the positive claims would allow you to free memory earlier while for negative claims you need to wait until the end of a session.</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">
<br>
</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
Regards,</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> </span>
<span style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
Felix</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> <br>
<br>
<br>
<span style="color:#5F5F5F"><br>
From: </span>"</span><span lang="KO" style="font-size:9.0pt">구철회</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif"> via SIS-DTN" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>>
<span style="color:#5F5F5F"><br>
To: </span>"<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>>
<span style="color:#5F5F5F"><br>
Date: </span>04/04/2022 10:15 <span style="color:#5F5F5F"><br>
Subject: </span>[Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing
<span style="color:#5F5F5F"><br>
Sent by: </span>"SIS-DTN" <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
</span><o:p></o:p></p>
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</span><br>
<span style="font-size:10.0pt;font-family:"Arial",sans-serif">Greetings,</span><span style="font-size:9.0pt;font-family:"Arial",sans-serif">
</span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif"> </span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">This is Cheol. I am developing an LTP reference implementation. During reading the LTP specification (RFC-5326), the preparation of reception claim in Report Segment makes me
confusing about why it is positive claim not negative claim for segments that were not received successfully (i.e., NAK).</span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif"> </span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">For reference, CFDP’s NAK PDU has the negative claim structure when it is requested to report missing PDUs. Does anyone know about the background of choosing the positive claim
for NAK operation in LTP?</span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">I think negative claim is simpler and more efficient in terms of overhead for sender and receiver both.</span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">I like to listen experts’ opinion on LTP operation and honestly hope it to be changed in newly coming LTP spec.</span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif"> </span><o:p></o:p></p>
<p style="margin:0in"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">Cheol</span><o:p></o:p></p>
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