<span style=" font-size:10pt;font-family:sans-serif">Good morning SLP-WG,
</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Being the AOS
Frame length a managed parameter and therefore mission dependent, its extension
to max 65536 octets does not make existing assets incompatible. In fact,
new missions wishing to re-use recurrent HW/SW, may still decide to keep
on using 2048 octets long AOS Frames. </span>
<br><span style=" font-size:10pt;font-family:sans-serif">If max AOS Frame
length gets extended, I'd rather go for expanding the 1st header pointer
to 16 bit if CCSDS Space Packet Protocol than constraining the max packet
length. </span>
<br><span style=" font-size:10pt;font-family:sans-serif">In fact, I would
discourage restricting max CCSDS packet length as this may introduce a
severe and unnecessary protocol overhead in systems using e.g. CFDP over
AOS.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">I hope this helps</span>
<br>
<br><span style=" font-size:10pt;font-family:Verdana">Best regards</span>
<br>
<br><span style=" font-size:10pt;font-family:Verdana"><b>Marco Rovatti</b></span>
<br><span style=" font-size:10pt;color:#0060a0;font-family:Verdana">Data
Handling and Avionics Engineer</span>
<br>
<br><img src=cid:_1_0D5CEE780D5CEA680030EE07C1258848 style="border:0px solid;"><span style=" font-size:10pt;font-family:Verdana">
</span>
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71 5655641</span>
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</b></span><span style=" font-size:10pt;font-family:Verdana">Keplerlaan
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<br>
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<br>
<br>
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<br>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</span><span style=" font-size:9pt;font-family:sans-serif">"Kazz,
Greg\(US 312B\) via SLS-SLP" <sls-slp@mailman.ccsds.org></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style=" font-size:9pt;font-family:sans-serif">"Kazz,
Greg (US 312B) via SLS-SLP" <sls-slp@mailman.ccsds.org></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Cc:
</span><span style=" font-size:9pt;font-family:sans-serif">"Andrea.Modenini@esa.int"
<Andrea.Modenini@esa.int>, "Sank, Victor J.\(GSFC-567.0\)\[SCIENCE
SYSTEMS AND APPLICATIONS INC\]" <victor.j.sank@nasa.gov>, "Rodriguez,
Shannon\(GSFC-5670\)" <shannon.rodriguez-1@nasa.gov></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Date:
</span><span style=" font-size:9pt;font-family:sans-serif">11/05/2022
19:39</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style=" font-size:9pt;font-family:sans-serif">[Sls-slp]
Extending the 1st Header Pointer in AOS to 16 bits to cover max Transfer
Frame length</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Sent
by: </span><span style=" font-size:9pt;font-family:sans-serif">"SLS-SLP"
<sls-slp-bounces@mailman.ccsds.org></span>
<br>
<hr noshade>
<br>
<br>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Dear
SLP WG,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">I’ve
been asked by Andrea Modenini, the chair of the C&S WG, to poll you
concerning their proposal below to utilize the 5 reserve bits in the M_PDU
header of the AOS Transfer Frame in order to extend the 1<sup>st</sup>
Header Pointer from 11 bits (2048 octet Maximum AOS Transfer Frame Size)
to 16 bits (65536 octet maximum AOS transfer frame). Note: USLP transfer
frame maximum is also 65536 octets.</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Please
provide me with your opinion by end of day May 17. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Here
is the proposal from Victor Sank and Shannon Rodriguez at NASA/GSFC:</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">We
agree that First Header Pointer must be able to point to first packet header
that is in the Packet Zone of the transfer frame. Even through the
packets can be very long, limited to a length of 65536 octets, and
may cover several transfer frames, the problem is where in the frame the
next packet starts. The 11 bit first header pointer is the limitation
since it would not be able to point far into the frame. But there
are 5 bits of reserved that can be used with the 11 bit, giving 16 total
and covering what we need. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">
We would have to couple the extension
of transfer frame lengths with making use of the reserved 5 bit in the
M_PDU Header. There is also an option that can be used. If
there is objection to extending the first header pointer to 16 bits, we
could still allow longer transfer frames with the restriction that the
packets used with these transfer frames are (temporarily) limited to 2048
octets. In the future if/when CCSDS agrees to the 16 bit first header
pointer, the restriction would be removed. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">CCSDS732.0-B-3
shows an M_PDU Header with the first header pointer as 11 bits but also
shows 5 bits of reserved. If we use the 5 bit we have 16 and can
point to 65536. </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><img src=cid:_4_0DC8E67C0DC8E4100030EE07C1258848 width=570 height=192 alt=cid348906*image003.png@01D86530.39956FC0 style="border:0px solid;"></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Best
regards,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri">Chair
SLP WG</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Greg
Kazz</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Principal
Engineer</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Technical
Group Supervisor,</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">312B
Project Protection, Project Software, and End to End Information System
Engineering</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Jet
Propulsion Laboratory</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">4800
Oak Grove Dr., M/S 301-490</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">Pasadena,
CA 91109</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">1+(818)393
6529(voice)</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">1+(818)393
6871(fax)</span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:11pt;font-family:Calibri">email:
greg.j.kazz@jpl.nasa.gov </span></p>
<p style="margin-top:0px;margin-Bottom:0px"><span style=" font-size:12pt;font-family:Calibri"> </span><tt><span style=" font-size:10pt">_______________________________________________<br>
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