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<p class="MsoNormal"><span style="color:#1F497D">As pointed out by Scott, I think current description of LTP is complete for what regards the services and related specification. LTPCLA specification is also quite clear in this respect. Further to this, section
2.3.2 already illustrates the services not supported by LTP, such as the in-order delivery. Maybe you can insert here the note you are suggesting, to show how in-order delivery might be ensured by protocol layers running on top of LTP, though not requiring
any interface support from LTP.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Best Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Tomaso<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray">————————————————————————</span><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D">
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</span><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray">Deutsches Zentrum für Luft- und Raumfahrt</span></b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray"> (DLR)</span><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D">
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</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray">German Aerospace Center</span><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D">
<br>
</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray">Institute of Communications and Navigation | Satellite Networks | Oberpfaffenhofen | 82234 Wessling | Germany</span><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D">
<o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray">Tomaso de Cola, Ph.D.</span></b><span style="color:#1F497D">
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</span><span lang="DE" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:dimgray">Telefon +49 8153 28-2156 | Telefax +49 8153 28-2844 |</span><span lang="DE" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D">
</span><span style="color:#1F497D"><a href="mailto:tomaso.decola@dlr.de"><span lang="DE" style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue">tomaso.decola@dlr.de</span></a></span><span lang="DE" style="color:#1F497D">
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</span><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><a href="http://www.dlr.de/kn/institut/abteilungen/san"><span lang="DE" style="color:blue">http://www.dlr.de/kn/institut/abteilungen/san</span></a></span><span style="color:#1F497D">
<span lang="DE"><o:p></o:p></span></span></p>
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<p class="MsoNormal"><span lang="DE" style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> sis-dtn-bounces@mailman.ccsds.org [mailto:sis-dtn-bounces@mailman.ccsds.org]
<b>On Behalf Of </b>Burleigh, Scott C (312G)<br>
<b>Sent:</b> Thursday, August 07, 2014 12:30 AM<br>
<b>To:</b> Scott, Keith L.; sis-dtn@mailman.ccsds.org<br>
<b>Subject:</b> [Sis-dtn] RE: JAXA RID on LTP -- LTP and Sequential Delivery<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Keith, you're right, there is nothing in the LTP specification that ever compels a receiving LTP engine to deliver green data in transmission order rather than
reception order (i.e., to reorder received green segments). <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">Scott<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:black">
<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a> [sis-dtn-bounces@mailman.ccsds.org] on behalf of Scott, Keith L. [kscott@mitre.org]<br>
<b>Sent:</b> Wednesday, August 06, 2014 10:00 AM<br>
<b>To:</b> <a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a><br>
<b>Subject:</b> [Sis-dtn] JAXA RID on LTP -- LTP and Sequential Delivery</span><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:14.0pt;color:black">Greetings,</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">Here’s my second question w.r.t. the JAXA RIDs. This one has to do with sequential (which I interpret to mean in-order) delivery with LTP.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">JAXA-PRA1415-09 states:</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">Sequential transportation is an essential function to control devices and
</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">LTP can provide sequential transportation over single hop with certain parameter of RFC5326.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">This aspect should be described in this document because it is an important potential of LTP.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">Is there something about RFC5326 that I missed? The Red-part data of a block is delivered atomically (so data is in-order within the Red Part I suppose) but I don’t think LTP guarantees anything
beyond that. In particular:</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in"><span style="font-size:14.0pt;font-family:Symbol;color:black">·</span><span style="font-size:7.0pt;font-family:"Times New Roman","serif";color:black">
</span><span style="font-size:14.0pt;color:black">The Red Part of a block might be delivered before, after, or in the middle of Green Data for that block.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-.25in"><span style="font-size:14.0pt;font-family:Symbol;color:black">·</span><span style="font-size:7.0pt;font-family:"Times New Roman","serif";color:black">
</span><span style="font-size:14.0pt;color:black">The relative arrival times of Red and Green data from multiple blocks transmitted simultaneously are undefined by the spec.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">The only way I know of to ensure in-order arrival of data would be to use only red data and to wait for the report indicating complete reception of one block before completing transmission of the
next (red) block. That’s possible, but it would be an implementation decision not part of the specification.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">Am I missing something here?</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">JAXA-PRA1415-10 states:</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">To control sequential transportation over multi-hop communication,
</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">RFC and Red Book should contain the description of the interface and</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">rule as SAP of LTP like the option of Green-Data.
</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">LTP can naturally support single hop sequential transportation,
</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:14.0pt;color:black">but multi hop transportation needs some handling of hop-to-hop interaction.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">The Delay-Tolerant Payload Conditioning (DTPC) in the BP-for-CCSDS book provides an in-order delivery service. As with the above (09) I don’t think there’s anything in the LTP spec (RFC5326 or
LTP-for-CCSDS) that says anything about providing in-order delivery of LTP blocks (or Green-part segments).</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black">Does anyone interpret these differently? If not then I’m going to suggest adding a NOTE specifically stating that in-order delivery is not an LTP service, but multi-hop (or single-hop, if BP is
deployed on both ends of the link) in-order delivery is achievable with BP and DTPC.</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> --keith</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:14.0pt;color:black"> </span><span style="color:black"><o:p></o:p></span></p>
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