<div dir="ltr">if you use only NAK, you won't be able to figure out whether the last packet made it. <div>Somewhere you need an ACK. Nacks can improve efficiency to avoid unneeded re-transmission but somewhere in the protocol you do need positive ACK.</div><div><br></div><div>v</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Apr 4, 2022 at 6:46 AM <<a href="mailto:Jeremy.Mayer@dlr.de">Jeremy.Mayer@dlr.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span lang="EN-GB">Vint,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">In this use-case, or generally? Since that sort of depends on stream vs message semantics. In the strictest possible sense, NORM can run in NACK-only mode. <u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Thanks,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB">Jeremy <u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-GB"><u></u> <u></u></span></p>
<div style="border-right:none;border-bottom:none;border-left:none;border-top:1pt solid rgb(225,225,225);padding:3pt 0in 0in">
<p class="MsoNormal"><b>From:</b> SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org" target="_blank">sis-dtn-bounces@mailman.ccsds.org</a>> <b>
On Behalf Of </b>Vint Cerf via SIS-DTN<br>
<b>Sent:</b> Monday, April 4, 2022 12:09 PM<br>
<b>To:</b> <a href="mailto:Felix.Flentge@esa.int" target="_blank">Felix.Flentge@esa.int</a><br>
<b>Cc:</b> <a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank">sis-dtn@mailman.ccsds.org</a>; <span style="font-family:"Malgun Gothic",sans-serif">
구철회</span> <<a href="mailto:chkoo@kari.re.kr" target="_blank">chkoo@kari.re.kr</a>><br>
<b>Subject:</b> Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">a system based solely on negative acks will not work.<u></u><u></u></p>
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<p class="MsoNormal">v<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Mon, Apr 4, 2022 at 6:08 AM Felix Flentge via SIS-DTN <<a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank">sis-dtn@mailman.ccsds.org</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal"><span style="font-size:10pt;font-family:Arial,sans-serif">Ah, yes, of course you are right.</span>
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<br>
<span style="font-size:10pt;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:10pt;font-family:Arial,sans-serif">Regards,</span> <br>
<span style="font-size:10pt;font-family:Arial,sans-serif">Felix</span> <br>
<br>
<br>
<br>
<span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(95,95,95)">From: </span><span style="font-size:9pt;font-family:Arial,sans-serif">"</span><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">구철회</span><span style="font-size:9pt;font-family:Arial,sans-serif">"
<</span><a href="mailto:chkoo@kari.re.kr" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">chkoo@kari.re.kr</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">></span>
<br>
<span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(95,95,95)">To: </span><span style="font-size:9pt;font-family:Arial,sans-serif"><</span><a href="mailto:Felix.Flentge@esa.int" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">Felix.Flentge@esa.int</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">></span>
<br>
<span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(95,95,95)">Cc: </span><span style="font-size:9pt;font-family:Arial,sans-serif">"</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">"
<</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">></span>
<br>
<span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(95,95,95)">Date: </span><span style="font-size:9pt;font-family:Arial,sans-serif">04/04/2022 11:58</span>
<br>
<span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(95,95,95)">Subject: </span><span style="font-size:9pt;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:9pt;font-family:Arial,sans-serif;color:rgb(95,95,95)">Sent by: </span><a href="mailto:chkoo@kari.re.kr" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">chkoo@kari.re.kr</span></a>
<u></u><u></u></p>
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<span style="font-size:12pt">Hi Felix,</span> <br>
<br>
<span style="font-size:12pt">I think current LTP spec quite works well with negative claim also. Consider below reception claim according to the LTP spec but negative claim.</span>
<br>
<br>
<span style="font-size:12pt">lower bound = 0</span> <br>
<span style="font-size:12pt">upper bound = 7000</span> <br>
<span style="font-size:12pt">negative reception claim count = 1</span> <br>
<span style="font-size:12pt">offset = 1000</span> <br>
<span style="font-size:12pt">length = 2000</span> <br>
<br>
<span style="font-size:12pt">it means a receiver is requesting block of segements which starts at 1000 and length is 2000, i.e., 1000 ~ 2999, for retransmission.</span>
<br>
<span style="font-size:12pt">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).</span>
<br>
<br>
<span style="font-size:12pt">Cheol</span> <u></u><u></u></p>
<p><b><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(0,98,225)">---------
</span></b><b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif;color:rgb(0,98,225)">원본</span></b><b><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(0,98,225)">
</span></b><b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif;color:rgb(0,98,225)">메일</span></b><b><span style="font-size:9pt;font-family:Arial,sans-serif;color:rgb(0,98,225)"> ---------</span></b><u></u><u></u></p>
<p class="MsoNormal"><br>
<b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">보낸사람</span></b><span style="font-size:9pt;font-family:Arial,sans-serif"> : <</span><a href="mailto:Felix.Flentge@esa.int" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">Felix.Flentge@esa.int</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">><b><br>
</b></span><b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">받는사람</span></b><span style="font-size:9pt;font-family:Arial,sans-serif"> : "</span><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">구철회</span><span style="font-size:9pt;font-family:Arial,sans-serif">"
<</span><a href="mailto:chkoo@kari.re.kr" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">chkoo@kari.re.kr</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">><b><br>
</b></span><b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">참조</span></b><span style="font-size:9pt;font-family:Arial,sans-serif"> : "</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">"
<</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">><b><br>
</b></span><b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">받은날짜</span></b><span style="font-size:9pt;font-family:Arial,sans-serif"> : 2022-04-04 (</span><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">월</span><span style="font-size:9pt;font-family:Arial,sans-serif">)
17:40:24<b><br>
</b></span><b><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">제목</span></b><span style="font-size:9pt;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:10pt;font-family:Arial,sans-serif">Hi Cheol,</span><span style="font-size:9pt;font-family:Arial,sans-serif">
<br>
</span><span style="font-size:10pt;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:9pt;font-family:Arial,sans-serif">
<br>
</span><span style="font-size:10pt;font-family:Arial,sans-serif"><br>
Regards,</span><span style="font-size:9pt;font-family:Arial,sans-serif"> </span>
<span style="font-size:10pt;font-family:Arial,sans-serif"><br>
Felix</span><span style="font-size:9pt;font-family:Arial,sans-serif"> <br>
<br>
<br>
<span style="color:rgb(95,95,95)"><br>
From: </span>"</span><span style="font-size:9pt;font-family:"Malgun Gothic",sans-serif">구철회</span><span style="font-size:9pt;font-family:Arial,sans-serif"> via SIS-DTN" <</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">>
<span style="color:rgb(95,95,95)"><br>
To: </span>"</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">" <</span><a href="mailto:sis-dtn@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">>
<span style="color:rgb(95,95,95)"><br>
Date: </span>04/04/2022 10:15 <span style="color:rgb(95,95,95)"><br>
Subject: </span>[Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing
<span style="color:rgb(95,95,95)"><br>
Sent by: </span>"SIS-DTN" <</span><a href="mailto:sis-dtn-bounces@mailman.ccsds.org" target="_blank"><span style="font-size:9pt;font-family:Arial,sans-serif">sis-dtn-bounces@mailman.ccsds.org</span></a><span style="font-size:9pt;font-family:Arial,sans-serif">>
</span><u></u><u></u></p>
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<span style="font-size:10pt;font-family:Arial,sans-serif">Greetings,</span><span style="font-size:9pt;font-family:Arial,sans-serif">
</span><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;font-family:Arial,sans-serif"> </span><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;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><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;font-family:Arial,sans-serif"> </span><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;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><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;font-family:Arial,sans-serif">I think negative claim is simpler and more efficient in terms of overhead for sender and receiver both.</span><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;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><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;font-family:Arial,sans-serif"> </span><u></u><u></u></p>
<p style="margin:0in"><span style="font-size:10pt;font-family:Arial,sans-serif">Cheol</span><u></u><u></u></p>
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<span style="font-size:10pt;font-family:Arial,sans-serif"><br>
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</blockquote>
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<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
</div>
<p class="MsoNormal">-- <u></u><u></u></p>
<div>
<div>
<div>
<p class="MsoNormal">Please send any postal/overnight deliveries to:<u></u><u></u></p>
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<p class="MsoNormal">Vint Cerf<u></u><u></u></p>
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<p class="MsoNormal">1435 Woodhurst Blvd <u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">until further notice<u></u><u></u></p>
</div>
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<p class="MsoNormal"><u></u> <u></u></p>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div>Please send any postal/overnight deliveries to:</div><div>Vint Cerf</div><div>1435 Woodhurst Blvd </div><div>McLean, VA 22102</div><div>703-448-0965</div><div><br></div><div>until further notice</div><div><br></div><div><br></div><div><br></div></div></div>