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<p class="MsoNormal" style="word-break:normal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Hi Cheol,<o:p></o:p></span></p>
<p class="MsoNormal" style="word-break:normal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Comments inlined
</span><span lang="EN-GB" style="font-size:11.0pt;font-family:Wingdings;mso-fareast-language:EN-US">J</span><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal" style="word-break:normal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="word-break:normal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal" style="word-break:normal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US">Jeremy<o:p></o:p></span></p>
<p class="MsoNormal" style="word-break:normal"><span lang="EN-GB" style="font-size:11.0pt;font-family:"Aptos",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">
</span><span style="font-size:11.0pt">구철회</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <chkoo@kari.re.kr>
<br>
<b>Sent:</b> Dienstag, 23. Juli 2024 04:38<br>
<b>To:</b> Felix Flentge <Felix.Flentge@esa.int><br>
<b>Cc:</b> sis-dtn@mailman.ccsds.org; sburleig.sb@gmail.com; Mayer, Jeremy <Jeremy.Mayer@dlr.de><br>
<b>Subject:</b> Some thoughts to the current HPRP draft (Section 1 - 4)<o:p></o:p></span></p>
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<p class="MsoNormal" align="left" style="text-align:left"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">Hi, colleagues.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">I just read the current HPRP draft and let me share some thoughts from me on the contents of Section 1 to 4.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">1) 4.1 HPRP Segment<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">It could be informative if we add a
</span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">Data Segment Section (Optional, variable)</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO">
after </span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">Header Extensions</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> field.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">Refer the figure on page. 10 of RFC 5326
</span><span lang="KO" style="mso-fareast-language:KO">“</span><span lang="EN-US" style="mso-fareast-language:KO">LTP
</span><span lang="KO" style="mso-fareast-language:KO">–</span><span lang="EN-US" style="mso-fareast-language:KO"> Specification</span><span lang="KO" style="mso-fareast-language:KO">”</span><span lang="EN-US" style="mso-fareast-language:KO">.<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM: Added “segment body”
<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">2) 4.1 HPRP Segment<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">Segment Type ID (bit field of 4
</span><span lang="KO" style="mso-fareast-language:KO">–</span><span lang="EN-US" style="mso-fareast-language:KO"> 5) could be extended to
</span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">bit field of 4
</span><span lang="KO" style="mso-fareast-language:KO">–</span><span lang="EN-US" style="mso-fareast-language:KO"> 7</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> to hold an indication of the
</span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">end of reliable data transmission in current session</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO">
like EORP or EOB in LTP (RFC-5326). Why are the EORP and EOB field deprecated in HPRP? Unlikely CP (Checkpoint), these are useful for space saving and good match with FPGA, e.g., a fastest way of generating an interrupt for this event.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">IMO, removing the descriptor of the
</span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">EORP</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> or
</span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">EOB</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> does not bring much benefit.
Sending the DAR (Data Acknowledgement Request) at the edge of the data transmission may not be efficient although DAR is quite good message scheme for asynchronous state check of data reception. I think DAR is better way than
</span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">CP</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> in LTP spec for this purpose.<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM: Those fields are deprecated to simplify the interfaces required for hardware acceleration; We made a simplifying assumption that, in an FPGA-accelerated implementation, the user
would implement all the complex state-keeping stuff within a CPU instead of an FPGA fabric. Therefore, we aimed to optimize the transfer of real-time signaling data between the CPU and FPGA. By simply copying the entire extension field (if it exists, and optionally
only if it’s a system extension), you facilitate use of DMA for transfers and allow a single interrupt (DMA transfer completed) to signal any and all protocol signaling.
<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">3) 4.1.8.3<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">The value session number length --> The value of the session number<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">(Q) The session number can be 0? I think it should be non-zero because 0 means, generally, the first index of an array or indicator that means no actions required.<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM: It can be, or randomly generated. In the existing implementation, we basically just used whatever was available (e.g. a potentially uninitialized variable)<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">4) 4.2.8.2.2.1<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"> Data Acknowledgement extensions must be acknowledged by the receiving (--> sending) engine via a metadata acknowledgment message.<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM: Updated text to clarify.<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">5) 4.3.2.2 Client Service ID<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:10.2pt"><span lang="EN-US" style="mso-fareast-language:KO">It could be informative if we add a description about how this field relate RFC-7116. Also, we may need to update this RFC-7116 document for adapting HPRP.<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM: I think this needs to be discussed.<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">6) 5.2.3<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"> Upon the end of reception --> Upon the reception of un-successful data acknowledgement<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM; Minor update bade<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">7) 5.2.4 Transmit Acknowledgement Request<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"> IMO, </span>
<span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">Timeout</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> could be more semantically appropriate
word than </span><span lang="KO" style="mso-fareast-language:KO">‘</span><span lang="EN-US" style="mso-fareast-language:KO">Interval</span><span lang="KO" style="mso-fareast-language:KO">’</span><span lang="EN-US" style="mso-fareast-language:KO"> in this context.<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US" style="mso-fareast-language:KO">JPM: We’re using the same value as the transmission interval on the Tx side, so I think this can stay unless someone has strong opinions about it.<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO">Cheol<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:KO"><o:p> </o:p></span></p>
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