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<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Hi, Peter. Actually, what you say about the DEM being used on top of the network and transport layers is exactly what I was thinking of: Space Packets seem like a great way to package application
(e.g., instrument, vehicle health, etc.) data that would be carried by underlying DTN. I definitely agree that we must not overload the Space Packet with features that belong at other layers of the stack, such as routing and network functions.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D">Scott<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt">From:</span></b><span style="font-size:11.0pt"> Shames, Peter M (312B)
<br>
<b>Sent:</b> Monday, April 23, 2018 3:49 PM<br>
<b>To:</b> Burleigh, Scott C (312B) <scott.c.burleigh@jpl.nasa.gov>; Greenberg, Edward (312B) <edward.greenberg@jpl.nasa.gov>; sls-slp@mailman.ccsds.org; Jonathan.J.Wilmot@NASA.gov<br>
<b>Cc:</b> Lee Pitts <robert.l.pitts@nasa.gov><br>
<b>Subject:</b> Re: [Sls-slp] Call for Use Cases of Space Packet Protocol<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The DEM was indeed Constellation's locally grown variant on the SPP, with added features similar to PUS. But please keep in mind that Constellation intended to use TCP/IP as a network and transport protocol,
and the DEM was to be used on top of those layers. Because of this it had no need to provide it's own routing and network functions, it just had to accommodate application layer exchanges, operations, and message topics.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">They could equally easily used SPP with secondary header extensions for the same purpose. I think we really must be careful to not overload this extensible application layer data structure with features that
really belong at other layers in the protocol stack. We have a rich set of protocols, starting from physical layer of the ISO stack, including data link, network/transport, messages & files, and these application layer data structures. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Let's not get them confused any more than they already are.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Peter<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="color:black">From: </span>
</b><span style="color:black">SLS-SLP <<a href="mailto:sls-slp-bounces@mailman.ccsds.org">sls-slp-bounces@mailman.ccsds.org</a>> on behalf of Scott Burleigh <<a href="mailto:scott.c.burleigh@jpl.nasa.gov">scott.c.burleigh@jpl.nasa.gov</a>><br>
<b>Date: </b>Monday, April 23, 2018 at 9:08 AM<br>
<b>To: </b>"Greenberg, Edward" <<a href="mailto:edward.greenberg@jpl.nasa.gov">edward.greenberg@jpl.nasa.gov</a>>, "<a href="mailto:sls-slp@mailman.ccsds.org">sls-slp@mailman.ccsds.org</a>" <<a href="mailto:sls-slp@mailman.ccsds.org">sls-slp@mailman.ccsds.org</a>>,
"Wilmot, Jonathan J. (GSFC-5820)" <<a href="mailto:Jonathan.J.Wilmot@NASA.gov">Jonathan.J.Wilmot@NASA.gov</a>><br>
<b>Cc: </b>Lee Pitts <<a href="mailto:robert.l.pitts@nasa.gov">robert.l.pitts@nasa.gov</a>><br>
<b>Subject: </b>Re: [Sls-slp] Call for Use Cases of Space Packet Protocol<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><a name="_MailOriginalBody"><span style="font-size:11.0pt">Ed, I think of the Space Packet as being the thing that the old Constellation project called a Data Exchange Message (DEM). I think it performs the same
function in the stack, and I suspect that it could easily carry all the same metadata that the DEM was supposed to carry.</span><o:p></o:p></a></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt"> </span><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt">Scott</span><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt"> </span><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><b><span style="font-size:11.0pt">From:</span></b></span><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt"> Greenberg, Edward (312B)
<br>
<b>Sent:</b> Sunday, April 22, 2018 7:37 AM<br>
<b>To:</b> </span></span><a href="mailto:sls-slp@mailman.ccsds.org"><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt">sls-slp@mailman.ccsds.org</span></span><span style="mso-bookmark:_MailOriginalBody"></span></a><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt">;
</span></span><a href="mailto:Jonathan.J.Wilmot@NASA.gov"><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt">Jonathan.J.Wilmot@NASA.gov</span></span><span style="mso-bookmark:_MailOriginalBody"></span></a><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt"><br>
<b>Cc:</b> Lee Pitts <</span></span><a href="mailto:robert.l.pitts@nasa.gov"><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt">robert.l.pitts@nasa.gov</span></span><span style="mso-bookmark:_MailOriginalBody"></span></a><span style="mso-bookmark:_MailOriginalBody"><span style="font-size:11.0pt">><br>
<b>Subject:</b> Call for Use Cases of Space Packet Protocol</span><o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"> <o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">There seems to be lots of new Use Cases for Space Packets then were considered in the original specification. For example:<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<span style="mso-bookmark:_MailOriginalBody"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>ESA has PUS<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<span style="mso-bookmark:_MailOriginalBody"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>Space Station has its own secondary header<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:1.0in;text-indent:-.25in;mso-list:l0 level1 lfo2">
<span style="mso-bookmark:_MailOriginalBody"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>Orion is looking for a secondary header<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Originally the Space Packet was an envelope for data transferred over single link (includes tunneling), now the packet is being looked at for network data transfer, local
onboard data transfer (including measurement broadcasting). <o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">It is possible that the role of the packet might change with the use of DTN bundles.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody">Just to take the broadest view: We currently have two forms of packets, should there be more or should even these be examined to determine if they should be blended into
a new packet design. <o:p></o:p></span></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="mso-bookmark:_MailOriginalBody"><span style="background:yellow;mso-highlight:yellow">Can we get each of you to send in your present and possibly desired Use Cases for our beloved Space Packet so that
we could determine its future.</span> </span><o:p></o:p></p>
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