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<p class="MsoNormal"><span style="color:#2F5597;mso-style-textfill-fill-color:#2F5597;mso-style-textfill-fill-alpha:100.0%">B2.1.3: UDP CL – Note on B2.1.3.2 says “It is desirable that BP agents endeavor to send bundles of such a size as not to require fragmentation
by the IP (Internet Protocol) layer. In practice this generally means keeping the size of the IP datagram (including the IP and UDP headers, plus the bundle) to no more than 1500 bytes.” <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">On one lunar mission we are supporting, the 1500-byte MTU bit us when the additional (outside of DTN) IPsec tunnel overhead was added and caused configuration issues on downstream IPsec routers.. I’ll go along
with recommending no fragmentation at the CL, but I don’t fully appreciate all of the ramifications of adding IPsec overhead to DTN traffic -- but it apparently required some routers to be set for jumbograms, so this might take some more thought..<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">Leigh<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Robert C Durst <durst@mitre.org><br>
<b>Date: </b>Wednesday, May 31, 2023 at 9:38 AM<br>
<b>To: </b>"Sipos, Brian J." <Brian.Sipos@jhuapl.edu>, "Sanchez Net, Marc (US 332H)" <marc.sanchez.net@jpl.nasa.gov>, "Jeremy.Mayer@dlr.de" <Jeremy.Mayer@dlr.de>, "sburleig.sb@gmail.com" <sburleig.sb@gmail.com>, "Torgerson, Jordan L (332M)" <jordan.l.torgerson@jpl.nasa.gov>,
"Felix.Flentge@esa.int" <Felix.Flentge@esa.int>, "keithlscott@gmail.com" <keithlscott@gmail.com><br>
<b>Cc: </b>"sis-dtn@mailman.ccsds.org" <sis-dtn@mailman.ccsds.org><br>
<b>Subject: </b>RE: [Sis-dtn] [EXTERNAL] RE: New version of LTP Corrigendum<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Folks, on a note that’s somewhat related to Brian’s message below, so far I’ve received precisely one Agency RID on BPv7, which is attached, FYI. It deals with the BPv7 Minimum Supported Bundle Size (sec 3.6):<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:.5in;line-height:11.75pt;mso-line-height-rule:exactly;punctuation-wrap:simple;text-autospace:none">
<b><span style="font-family:"Times New Roman",serif;color:#0F0F0F">3.6 MINIMUM SUPPORTED BUNDLE SIZE<o:p></o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:.35pt;margin-right:0in;margin-bottom:0in;margin-left:30.7pt;margin-bottom:.0001pt;punctuation-wrap:simple;text-autospace:none">
<b><span style="font-size:10.0pt;font-family:"Times New Roman",serif"><o:p> </o:p></span></b></p>
<p class="MsoNormal" style="mso-margin-top-alt:0in;margin-right:15.95pt;margin-bottom:0in;margin-left:35.8pt;margin-bottom:.0001pt;text-indent:.15pt;line-height:102%;punctuation-wrap:simple;text-autospace:none">
<span style="font-family:"Times New Roman",serif;color:#0F0F0F">Conformant CCSDS implementations shall be able to forward and</span><span style="font-family:"Times New Roman",serif;color:#313131">/</span><span style="font-family:"Times New Roman",serif;color:#0F0F0F">or
deliver bundles whose total size, including all extension blocks, is less than or equal to 10*2<sup>20</sup> bytes (10 MB).<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:11.4pt;margin-right:0in;margin-bottom:0in;margin-left:35.85pt;margin-bottom:.0001pt;punctuation-wrap:simple;text-autospace:none">
<span style="font-family:"Times New Roman",serif;color:#0F0F0F">NOTE - Disposition of larger bundles is implementation-specific.<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The RID says: <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">“Add details that show considerations for minimum size have been considered for network implementation.
<o:p></o:p></p>
<p class="MsoNormal">The Note that disposition of larger bundles is implementation-specific needs to be augmented to show that
<o:p></o:p></p>
<p class="MsoNormal">the impacts of this large bundle size have been considered for the various ways that networks could meet
<o:p></o:p></p>
<p class="MsoNormal">this requirement with the convergence layers. It’s difficult to understand how an UDP or SPP Convergence-Layer<o:p></o:p></p>
<p class="MsoNormal">would satisfy this requirement. It would be helpful to provide examples based on the CLAs specified in this document.”<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In Normative Annex B, we specify 5 CLAs, and assert that a compliant BP implementation shall implement at least one of them. As a result, a compliant implementation need implement
<i>no more</i> than one of them. By implication, since any of the CLAs specified might be the
<i>only</i> CLA available, the requirement from Section 3.6 must be able to be met by any of the CLAs.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">B2.1.2: TCP CL – stream-oriented CL; no inherent limitations on Bundle Size.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">B2.1.3: UDP CL – Note on B2.1.3.2 says “<span style="color:#0F0F0F">It is desirable that BP agents endeavor to send bundles of such a size as not to require fragmentation by the IP (Internet Protocol) layer. In practice this generally
means keeping the size of the IP datagram (including the IP and UDP headers, plus the bundle) to no more than 1500 bytes.”
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">Probably not the answer he wants, particularly in the context of a 10MB bundle. How does a UDP CL meet the requirement specified in 3.6? If the UDP CL *<b>cannot</b>* meet the requirement specified in 3.6,
how should we proceed? Must the Bundle be fragmented into some number of fragmentary bundles that fit into a sequence of 150+ 65507-byte UDP payloads (or 6700+ 1472-byte UDP payloads)?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">B2.1.4: LTP CL – is there a length limitation on LTP ADUs (Blocks)? I didn’t see one in the RFC or the Blue Book<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">B2.1.5: SPP – B2.1.5.1 notes that the maximum size of a bundle is <= 65535. Is Bundle fragmentation therefore the only way to accommodate the requirement of section 3.6?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">B2.1.6: EPP – 4GB MTU meets the section 3.6 requirement.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F">So, for TCP, LTP, and EPP there’s no issue with the requirement in 3.6. For UDP and SPP, is Bundle Fragmentation the only feasible approach?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F">RFC 9171 section 5.9 permits in-transit reassembly (“</span><span style="font-size:10.0pt;font-family:NotoSerif-Regular;color:#222222">an ADU also be reassembled at some other node
on the path to the destination.”). </span><span style="color:#0F0F0F">The motivator for that might be to remove redundant bundle headers in order to reduce overhead before forwarding a large bundle over a (potentially not-yet-available) constrained link.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F">Is it the sense of this group that this is correct? Would an appropriate response to the RID be to add to the note on 3.6 a sentence to the effect of the following: “…</span><span style="font-family:"Times New Roman",serif;color:#0F0F0F">is
implementation-specific. For CLAs that have maximum size limits that are less than this 10MB requirement (e.g., UDP, B2.1.3 and SPP, B2.1.5), Bundle Fragmentation and Reassembly (refer to RFC 9171 sections 5.8 and 5.9) are available to mitigate the limitation.”
</span><span style="color:#0F0F0F"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F">Any sense of the reaction to this not-so-satisfying response?<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="color:#0F0F0F">Thanks,<br>
Bob <o:p></o:p></span></p>
<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><b>From:</b> SIS-DTN <sis-dtn-bounces@mailman.ccsds.org> <b>
On Behalf Of </b>Sipos, Brian J. via SIS-DTN<br>
<b>Sent:</b> Wednesday, May 31, 2023 11:04 AM<br>
<b>To:</b> Sanchez Net, Marc (US 332H) <marc.sanchez.net@jpl.nasa.gov>; Jeremy.Mayer@dlr.de; sburleig.sb@gmail.com; Torgerson, J. Leigh (US 332C) <jordan.l.torgerson@jpl.nasa.gov>; Felix.Flentge@esa.int; keithlscott@gmail.com<br>
<b>Cc:</b> sis-dtn@mailman.ccsds.org<br>
<b>Subject:</b> Re: [Sis-dtn] [EXTERNAL] RE: New version of LTP Corrigendum<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Marc, for my own purposes the one reason for using unreliable LTP is to take advantage of the segmentation of larger-than-MTU blocks. It’s a useful thing on its own separate from other capabilities of LTP. Similar
to some of these other recommendations, it would be helpful for implementations to know “if you are able to choose block sizes then here is a recommendation … Otherwise if you are using green block segmentation then here are some considerations (about timing
and resource leaks) …”<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">I think it’s better for an designer/implementer to be aware of potential issues and head them off than to try to ignore or impose restrictions on the service which would prohibit existing use cases.<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"><b>From:</b> SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b>Sanchez Net, Marc (US 332H) via SIS-DTN<br>
<b>Sent:</b> Wednesday, May 31, 2023 8:55 AM<br>
<b>To:</b> <a href="mailto:Jeremy.Mayer@dlr.de">Jeremy.Mayer@dlr.de</a>; <a href="mailto:sburleig.sb@gmail.com">
sburleig.sb@gmail.com</a>; Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>;
<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>; <a href="mailto:sis-dtn@mailman.ccsds.org">
sis-dtn@mailman.ccsds.org</a>; <a href="mailto:keithlscott@gmail.com">keithlscott@gmail.com</a><br>
<b>Subject:</b> [EXT] Re: [Sis-dtn] [EXTERNAL] RE: New version of LTP Corrigendum<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I am unconvinced either way, to be honest. I agree with Jeremy forcing the LTP engine to know the contact plan is not great, but having another “stale session timeout” seems an equally non-ideal solution. Would all these problems “go away”
if we force in the spec that a green block always be transmitted as a single green segment? But then the block size must be matched to the underlying link MTU (or transmission size used by the mission) which is <=65 kB for transfer frames, I believe. Would
that be too restrictive if we sent streaming video over LTP green?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">-----------------------------------------------------------------------------------------------------------------------<o:p></o:p></p>
<p class="MsoNormal">Marc Sanchez Net (332H)<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:gray">Telecommunications Engineer</span><o:p></o:p></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:gray">Jet Propulsion Laboratory<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:gray">Cell:</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#222222"> </span><span style="color:black"><a href="mailto:(617)%20953-7977"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0563C1">(617)
953-7977</span></a></span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0070C0">
</span><span style="font-size:10.0pt;color:gray">|</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0070C0">
</span><span style="font-size:10.0pt;color:gray">Email:</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#222222"> </span><span style="color:black"><a href="mailto:marc.sanchez.net@jpl.nasa.gov"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">marc.sanchez.net@jpl.nasa.gov</span></a></span><span style="font-size:9.5pt;font-family:"Arial",sans-serif;color:#222222"><o:p></o:p></span></p>
<p class="MsoNormal">-----------------------------------------------------------------------------------------------------------------------<o:p></o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> <a href="mailto:Jeremy.Mayer@dlr.de">Jeremy.Mayer@dlr.de</a> <<a href="mailto:Jeremy.Mayer@dlr.de">Jeremy.Mayer@dlr.de</a>>
<br>
<b>Sent:</b> Wednesday, May 31, 2023 1:05 AM<br>
<b>To:</b> <a href="mailto:sburleig.sb@gmail.com">sburleig.sb@gmail.com</a>; Sanchez Net, Marc (US 332H) <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>; Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>;
<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>; <a href="mailto:sis-dtn@mailman.ccsds.org">
sis-dtn@mailman.ccsds.org</a>; <a href="mailto:keithlscott@gmail.com">keithlscott@gmail.com</a><br>
<b>Subject:</b> RE: [Sis-dtn] [EXTERNAL] RE: New version of LTP Corrigendum<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Realistically, I agree, the LTP engine should probably be aware of either the contact plan OR the status of the downlink. That being said, I don’t think that’s a dependency which we want to force, due to the “perpetual
downlink” use-case (ISS). There’s nothing stopping me from running a single LTP link from now until the end of time, unaware of the status of the underlying link. Of course, there’s the caveat that green sessions may be transmitted into the void, never to
be seen again.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">That being said, the “last green block” problem is insidious: In a nominal downlink (e.g. with minimal out-of-order arrival and loss), we can use the EOB as a signal that the block should be delivered. However, if the
EOB is out-of-order, there’s a problem: the application shouldn’t have to expect that data from the same session may arrive twice. The only way to really deal with this in the face of out-of-order/missing arrivals is to track the completeness of a green session.
If the EOB block is delivered while data is still missing, we ignore it and “hold” the session until a user-specified timeout. In LTPv2, we called this the “stale session timeout”. If more data is delivered into one of these pending sessions, it can still
be enqueued and delivered upon timeout. This allows us to treat out of order sessions and those where the EOB is missed in the same way.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Jeremy<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b>sburleig.sb--- via SIS-DTN<br>
<b>Sent:</b> Tuesday, May 30, 2023 11:55 PM<br>
<b>To:</b> 'Sanchez Net, Marc (US 332H)' <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>; 'Torgerson, J. Leigh (US 332C)' <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>; 'Felix Flentge'
<<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>>; 'Dr. Keith L Scott via SIS-DTN' <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>>;
<a href="mailto:keithlscott@gmail.com">keithlscott@gmail.com</a><br>
<b>Subject:</b> Re: [Sis-dtn] [EXTERNAL] RE: New version of LTP Corrigendum<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Marc, good question. My thought on this is that LTP needs to be aware of the “contact plan” in order to know when to pause and resume the “red” timers. Given this, the LTP engine should be able to infer that cessation of green block segment
reception is due to the termination of the pass. At that point we have a matter of policy. If it’s known that green block transmission is always supposed to happen far enough before the end of the pass to enable complete reception, then the end of the pass
signifies that any currently incomplete block is not going to be completed and the block’s current incomplete contents can be delivered. If not, then maybe the current state of that incomplete final block should be sustained until the start of the next pass
enables further reception of that block’s segments.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Of course, sticking to small green blocks that are transmitted in single green segments makes the whole issue go away.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Scott<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Sanchez Net, Marc (US 332H) <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>
<br>
<b>Sent:</b> Tuesday, May 30, 2023 1:18 PM<br>
<b>To:</b> <a href="mailto:sburleig.sb@gmail.com">sburleig.sb@gmail.com</a>; Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>; 'Felix Flentge' <<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>>;
'Dr. Keith L Scott via SIS-DTN' <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>>;
<a href="mailto:keithlscott@gmail.com">keithlscott@gmail.com</a><br>
<b>Cc:</b> Gao, Jay L (US 332C) <<a href="mailto:jay.l.gao@jpl.nasa.gov">jay.l.gao@jpl.nasa.gov</a>>; Richard, Nate J (US 332C) <<a href="mailto:nathaniel.j.richard@jpl.nasa.gov">nathaniel.j.richard@jpl.nasa.gov</a>><br>
<b>Subject:</b> RE: [EXTERNAL] RE: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">All,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">A quick update to the draft LTP corrigendum with a few more items to make sure some of the issues being brought up in this email chain don’t fall through the cracks.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Also, a minor note on Scott’s comment that “<i>the arrival of the first segment of the next “green” block is a simpler and perhaps more accurate (configuration-free) means of determining that it is time to deliver the current block</i>”:
How does the receiving LTP engine handle the very last LTP block of a pass? Without a timer, would it ever be released to the application? I hate to add new timers, but I do not see how to get around it in this this corner case.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">-----------------------------------------------------------------------------------------------------------------------<o:p></o:p></p>
<p class="MsoNormal">Marc Sanchez Net (332H)<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:gray">Telecommunications Engineer</span><o:p></o:p></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:gray">Jet Propulsion Laboratory<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;color:gray">Cell:</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#222222"> </span><span style="color:black"><a href="mailto:(617)%20953-7977"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0563C1">(617)
953-7977</span></a></span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0070C0">
</span><span style="font-size:10.0pt;color:gray">|</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0070C0">
</span><span style="font-size:10.0pt;color:gray">Email:</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#222222"> </span><span style="color:black"><a href="mailto:marc.sanchez.net@jpl.nasa.gov"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">marc.sanchez.net@jpl.nasa.gov</span></a></span><span style="font-size:9.5pt;font-family:"Arial",sans-serif;color:#222222"><o:p></o:p></span></p>
<p class="MsoNormal">-----------------------------------------------------------------------------------------------------------------------<o:p></o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> <a href="mailto:sburleig.sb@gmail.com">sburleig.sb@gmail.com</a> <<a href="mailto:sburleig.sb@gmail.com">sburleig.sb@gmail.com</a>>
<br>
<b>Sent:</b> Tuesday, May 30, 2023 8:13 AM<br>
<b>To:</b> Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>; 'Felix Flentge' <<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>>; Sanchez Net, Marc (US 332H) <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>;
'Dr. Keith L Scott via SIS-DTN' <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><br>
<b>Cc:</b> Gao, Jay L (US 332C) <<a href="mailto:jay.l.gao@jpl.nasa.gov">jay.l.gao@jpl.nasa.gov</a>>; Richard, Nate J (US 332C) <<a href="mailto:nathaniel.j.richard@jpl.nasa.gov">nathaniel.j.richard@jpl.nasa.gov</a>><br>
<b>Subject:</b> RE: [EXTERNAL] RE: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Guys, a thought on this.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In “red” transmission you expect out-of-order segment arrival on a routine basis, because every retransmitted bundle will arrive out of order. There are timers in the protocol to support the operation of the retransmission procedures.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In “green” transmission you cannot have out-of-order segment arrival if you size your blocks in such a way that each block is transmitted in a single segment. I believe users will typically adopt this model, as “green” data will normally
be data for which minimized delay is more important than reliability (otherwise they would use “red” transmission).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In “green” transmission where the blocks are large enough to require transmission in multiple segments you have to wait for an entire block to arrive – or until you are confident that any missing segments were actually lost rather than
simply forwarded out of order – before delivering the contents of the block. But there’s no re-transmission to avoid, because the transmission is “green”, right? If you wanted retransmission you would have used “red”.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">So in that event I would suggest that the arrival of the first segment of the next “green” block is a simpler and perhaps more accurate (configuration-free) means of determining that it is time to deliver the current block – complete or
incomplete – and let the application figure out what to do about the missing data.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Scott<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>
<br>
<b>Sent:</b> Tuesday, May 30, 2023 7:54 AM<br>
<b>To:</b> Felix Flentge <<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>>;
<a href="mailto:sburleig.sb@gmail.com">sburleig.sb@gmail.com</a>; Sanchez Net, Marc (US 332H) <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>; 'Dr. Keith L Scott via SIS-DTN' <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><br>
<b>Cc:</b> Gao, Jay L (US 332C) <<a href="mailto:jay.l.gao@jpl.nasa.gov">jay.l.gao@jpl.nasa.gov</a>>; Richard, Nate J (US 332C) <<a href="mailto:nathaniel.j.richard@jpl.nasa.gov">nathaniel.j.richard@jpl.nasa.gov</a>><br>
<b>Subject:</b> Re: [EXTERNAL] RE: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks Felix – <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Agreed - A statement warning about how implementations should be wary of out-of-order deliveries would be useful in the corrigendum..<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">regards,<o:p></o:p></p>
<p class="MsoNormal">Leigh<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span lang="EN-GB" style="font-size:12.0pt;color:black">From:
</span></b><span lang="EN-GB" style="font-size:12.0pt;color:black">Felix Flentge <</span><a href="mailto:Felix.Flentge@esa.int"><span lang="EN-GB" style="font-size:12.0pt">Felix.Flentge@esa.int</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">><br>
<b>Date: </b>Monday, May 29, 2023 at 11:47 PM<br>
<b>To: </b>"Torgerson, Jordan L (332M)" <</span><a href="mailto:jordan.l.torgerson@jpl.nasa.gov"><span lang="EN-GB" style="font-size:12.0pt">jordan.l.torgerson@jpl.nasa.gov</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">>, "</span><a href="mailto:sburleig.sb@gmail.com"><span lang="EN-GB" style="font-size:12.0pt">sburleig.sb@gmail.com</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">"
<</span><a href="mailto:sburleig.sb@gmail.com"><span lang="EN-GB" style="font-size:12.0pt">sburleig.sb@gmail.com</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">>, "Sanchez Net, Marc (US 332H)" <</span><a href="mailto:marc.sanchez.net@jpl.nasa.gov"><span lang="EN-GB" style="font-size:12.0pt">marc.sanchez.net@jpl.nasa.gov</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">>,
"'Dr. Keith L Scott via SIS-DTN'" <</span><a href="mailto:sis-dtn@mailman.ccsds.org"><span lang="EN-GB" style="font-size:12.0pt">sis-dtn@mailman.ccsds.org</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">><br>
<b>Cc: </b>"Gao, Jay L (US 332C)" <</span><a href="mailto:jay.l.gao@jpl.nasa.gov"><span lang="EN-GB" style="font-size:12.0pt">jay.l.gao@jpl.nasa.gov</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">>, "Richard, Nate J (US 332C)" <</span><a href="mailto:nathaniel.j.richard@jpl.nasa.gov"><span lang="EN-GB" style="font-size:12.0pt">nathaniel.j.richard@jpl.nasa.gov</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">><br>
<b>Subject: </b>RE: [EXTERNAL] RE: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
</div>
<p class="MsoNormal"><span lang="EN-GB">Hi Leigh,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Yes, we also have systematic out-of-order in EO or L2 missions as different physical channels may be used (with maybe different rates and different PDU sizes). With ‘implementation issue’ I don’t mean that it is not important
but I would like to avoid making it normative as we want to avoid ‘changing the standard’ which would require interop testing.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">By any means, we should have a statement that in case you may have out-of-order delivery it is recommended to implement timer to wait for out-of-order segments to avoid re-transmission (we will add a similar statement
to CFDP for the next release).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span lang="EN-GB">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Felix<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="margin-left:.5in"><b>From:</b> Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>>
<br>
<b>Sent:</b> Thursday, May 25, 2023 6:22 PM<br>
<b>To:</b> Felix Flentge <<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>>;
<a href="mailto:sburleig.sb@gmail.com">sburleig.sb@gmail.com</a>; Sanchez Net, Marc (US 332H) <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>; 'Dr. Keith L Scott via SIS-DTN' <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><br>
<b>Cc:</b> Gao, Jay L (US 332C) <<a href="mailto:jay.l.gao@jpl.nasa.gov">jay.l.gao@jpl.nasa.gov</a>>; Richard, Nate J (US 332C) <<a href="mailto:nathaniel.j.richard@jpl.nasa.gov">nathaniel.j.richard@jpl.nasa.gov</a>><br>
<b>Subject:</b> Re: [EXTERNAL] RE: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in">Thanks Felix – <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:.5in">One comment is that in deep space use of DTN, we would expect that out-of-order delivery would be the rule, rather than the exception – if it takes 40 min RTT to recover a missing segment from Mars, waiting for
it to ensure in-order delivery to some application would make ops impossible. (One must design one’s applications to be “aware” of the operational environment of course..)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:.5in">We haven’t used both LTP red/green at the same time in our testing and real-world ops as far as I know, but I suspect that recommending that red and green be in different sessions would be a good idea, if nothing
else but to make troubleshooting easier! (Nate and Jay may have some thoughts based on our lunar ops with KPLO so I cc:d them..)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:.5in">regards<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">Leigh<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="margin-left:.5in"><b><span lang="EN-GB" style="font-size:12.0pt;color:black">From:
</span></b><span lang="EN-GB" style="font-size:12.0pt;color:black">Felix Flentge <</span><a href="mailto:Felix.Flentge@esa.int"><span lang="EN-GB" style="font-size:12.0pt">Felix.Flentge@esa.int</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">><br>
<b>Date: </b>Thursday, May 25, 2023 at 4:56 AM<br>
<b>To: </b>"</span><a href="mailto:sburleig.sb@gmail.com"><span lang="EN-GB" style="font-size:12.0pt">sburleig.sb@gmail.com</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">" <</span><a href="mailto:sburleig.sb@gmail.com"><span lang="EN-GB" style="font-size:12.0pt">sburleig.sb@gmail.com</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">>,
"Sanchez Net, Marc (US 332H)" <</span><a href="mailto:marc.sanchez.net@jpl.nasa.gov"><span lang="EN-GB" style="font-size:12.0pt">marc.sanchez.net@jpl.nasa.gov</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">>, "'Dr. Keith L Scott via SIS-DTN'"
<</span><a href="mailto:sis-dtn@mailman.ccsds.org"><span lang="EN-GB" style="font-size:12.0pt">sis-dtn@mailman.ccsds.org</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">><br>
<b>Cc: </b>"Torgerson, Jordan L (332M)" <</span><a href="mailto:jordan.l.torgerson@jpl.nasa.gov"><span lang="EN-GB" style="font-size:12.0pt">jordan.l.torgerson@jpl.nasa.gov</span></a><span lang="EN-GB" style="font-size:12.0pt;color:black">><br>
<b>Subject: </b>[EXTERNAL] RE: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB">Hi,<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB">I agree with the modifications below.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB">Some additional points:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span lang="EN-GB" style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-GB">I would propose to also deprecate Service Data Aggregation (it is currently mandatory). Unless, I am overlooking something, it is not an interoperable mechanism as there is no generic way to determine the length
of a client data capsule. Also, for BP/LTP the updated BP standard will describe an aggregation mechanism (CBOR length information + bundle IIRC).<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span lang="EN-GB" style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-GB">Should we discourage use of mixed sessions (on the other hand LTP green is optional anyway)?<o:p></o:p></span></p>
<p class="MsoListParagraph" style="margin-left:1.0in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span lang="EN-GB" style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span lang="EN-GB">For the two additional issues, we could add that this is an implementation issue and that implementation may want to introduce these additional timers in case they (routinely) expect out-of-order delivery<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB">Regards,<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB">Felix<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span lang="EN-GB"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><b>From:</b> SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b>sburleig.sb--- via SIS-DTN<br>
<b>Sent:</b> Thursday, May 18, 2023 1:23 AM<br>
<b>To:</b> 'Sanchez Net, Marc (US 332H)' <<a href="mailto:marc.sanchez.net@jpl.nasa.gov">marc.sanchez.net@jpl.nasa.gov</a>>; 'Dr. Keith L Scott via SIS-DTN' <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><br>
<b>Cc:</b> 'Torgerson, J. Leigh (US 332C)' <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>><br>
<b>Subject:</b> Re: [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-left:1.0in">Marc, FWIW, I agree about deprecating LTP security and I am likewise skeptical that adding more timers is a good idea; that sounds like a way to work around a design element that hasn’t been thought through completely.<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">Scott<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><b>From:</b> SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b>Sanchez Net, Marc (US 332H) via SIS-DTN<br>
<b>Sent:</b> Tuesday, May 16, 2023 7:05 PM<br>
<b>To:</b> Dr. Keith L Scott via SIS-DTN <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><br>
<b>Cc:</b> Torgerson, J. Leigh (US 332C) <<a href="mailto:jordan.l.torgerson@jpl.nasa.gov">jordan.l.torgerson@jpl.nasa.gov</a>><br>
<b>Subject:</b> [Sis-dtn] New version of LTP Corrigendum<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black">All,<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black">Please find attached a new version of the LTP corrigendum with some modifications including:<o:p></o:p></span></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.5in;text-indent:-.25in;mso-list:l0 level1 lfo4">
<![if !supportLists]><span style="font-size:10.0pt;font-family:Symbol;color:black"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:black">Comparison between LTP and "the new protocol" has been reduced. This in part motivated by the fact that we have demonstrated ~4 Gbps rates with ION's LTP implementation, which is more than sufficient
for deep space links (e.g., even in future trunk lines between Earth and Mars, data rates of 4 Gbps are never exceeded).<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.5in;text-indent:-.25in;mso-list:l0 level1 lfo4">
<![if !supportLists]><span style="font-size:10.0pt;font-family:Symbol;color:black"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:black">I have added two possible additions to the technical corrigendum based on work done by Brian and people at GRC. They are all optional (MAY) statements and I believe can be implemented without additional
managed parameters (and timers).<o:p></o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;margin-left:1.5in;text-indent:-.25in;mso-list:l0 level1 lfo4">
<![if !supportLists]><span style="font-size:10.0pt;font-family:Symbol;color:black"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]><span style="color:black">Brian has commented on two additional issues (see
</span><a href="https://urldefense.us/v3/__https:/github.com/nasa/HDTN/issues/22__;!!PvBDto6Hs4WbVuu7!J3wEpyPHlAiGcXO0VDc8uO1zb9BOrpYLw3dw6BHPigpmcy0Q4f8gxX6hHLnQOqg_AVxEg_MYrByNRr1urhAp-KViTuP33vk9LEw4$" title="https://github.com/nasa/HDTN/issues/22">here</a><span style="color:black"> and
</span><a href="https://urldefense.us/v3/__https:/github.com/nasa/HDTN/issues/24__;!!PvBDto6Hs4WbVuu7!J3wEpyPHlAiGcXO0VDc8uO1zb9BOrpYLw3dw6BHPigpmcy0Q4f8gxX6hHLnQOqg_AVxEg_MYrByNRr1urhAp-KViTuP33uBoiHHY$" title="https://github.com/nasa/HDTN/issues/24">here</a><span style="color:black">),
but those seem to require additional timers that would need to be managed, so I am unconvinced it is worth the extra complexity. Brian, please correct me if I am wrong.<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black">Finally, I think the note at the beginning of Section 3.9 of the current CCSDS LTP spec should be modified to explicitly state that LTP security should not be used and, instead, implementers
should rely on security mechanisms provided by other parts of the CCSDS protocol stack, be it SDLS or BPSec. Thoughts on this point? <o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><a href="https://urldefense.us/v3/__https:/github.com/nasa/HDTN/issues/24__;!!PvBDto6Hs4WbVuu7!J3wEpyPHlAiGcXO0VDc8uO1zb9BOrpYLw3dw6BHPigpmcy0Q4f8gxX6hHLnQOqg_AVxEg_MYrByNRr1urhAp-KViTuP33uBoiHHY$" target="_blank"><span style="color:windowtext;text-decoration:none"><span style="color:blue;border:solid windowtext 1.0pt;padding:0in"><img border="0" width="240" height="120" style="width:2.5in;height:1.25in" id="_x0000_i1026" src="cid:~WRD0000.jpg" alt="Image removed by sender."></span></span></a><o:p></o:p></p>
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<p class="MsoNormal"><a href="https://urldefense.us/v3/__https:/github.com/nasa/HDTN/issues/24__;!!PvBDto6Hs4WbVuu7!J3wEpyPHlAiGcXO0VDc8uO1zb9BOrpYLw3dw6BHPigpmcy0Q4f8gxX6hHLnQOqg_AVxEg_MYrByNRr1urhAp-KViTuP33uBoiHHY$" target="_blank"><span style="font-size:16.0pt;font-family:"Segoe UI Light",sans-serif;text-decoration:none">Defer
data retransmission with out-of-order report segments · Issue #24 · nasa/HDTN</span></a><span style="font-size:16.0pt;font-family:"Segoe UI Light",sans-serif"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Segoe UI",sans-serif;color:#666666">When the network is causing out-of-order segment reception it is possible that one or more synchronous reception reports are received either out-of-order or
within a short time window, possibly fol...<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Segoe UI",sans-serif;color:#A6A6A6">github.com<o:p></o:p></span></p>
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<p class="MsoNormal"><a href="https://urldefense.us/v3/__https:/github.com/nasa/HDTN/issues/22__;!!PvBDto6Hs4WbVuu7!J3wEpyPHlAiGcXO0VDc8uO1zb9BOrpYLw3dw6BHPigpmcy0Q4f8gxX6hHLnQOqg_AVxEg_MYrByNRr1urhAp-KViTuP33vk9LEw4$" target="_blank"><span style="color:windowtext;text-decoration:none"><span style="color:blue;border:solid windowtext 1.0pt;padding:0in"><img border="0" width="240" height="120" style="width:2.5in;height:1.25in" id="_x0000_i1025" src="cid:~WRD0000.jpg" alt="Image removed by sender."></span></span></a><o:p></o:p></p>
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<p class="MsoNormal"><a href="https://urldefense.us/v3/__https:/github.com/nasa/HDTN/issues/22__;!!PvBDto6Hs4WbVuu7!J3wEpyPHlAiGcXO0VDc8uO1zb9BOrpYLw3dw6BHPigpmcy0Q4f8gxX6hHLnQOqg_AVxEg_MYrByNRr1urhAp-KViTuP33vk9LEw4$" target="_blank"><span style="font-size:16.0pt;font-family:"Segoe UI Light",sans-serif;text-decoration:none">Defer
synchronous reception report with out-of-order data segments · Issue #22 · nasa/HDTN</span></a><span style="font-size:16.0pt;font-family:"Segoe UI Light",sans-serif"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Segoe UI",sans-serif;color:#666666">When red part data is segmented and delivered to the receiving engine out-of-order, the checkpoint(s) and EORP can be received before the earlier-in-block data
segments. If a synchronous report is ...<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Segoe UI",sans-serif;color:#A6A6A6">github.com<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:black">Thanks,<o:p></o:p></span></p>
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<div id="Signature">
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<p class="MsoNormal" style="margin-left:1.0in">-----------------------------------------------------------------------------------------------------------------------<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">Marc Sanchez Net (332H)<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="font-size:10.0pt;color:gray">Telecommunications Engineer</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in;background:white"><span style="font-size:10.0pt;color:gray">Jet Propulsion Laboratory</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in;background:white"><span style="font-size:10.0pt;color:gray">Cell:</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#222222"> </span><span style="color:black"><a href="mailto:(617)%20953-7977"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">(617)
953-7977</span></a></span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0070C0">
</span><span style="font-size:10.0pt;color:gray">|</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#0070C0">
</span><span style="font-size:10.0pt;color:gray">Email:</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#222222"> </span><span style="color:black"><a href="mailto:marc.sanchez.net@jpl.nasa.gov"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">marc.sanchez.net@jpl.nasa.gov</span></a></span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">-----------------------------------------------------------------------------------------------------------------------<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
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