<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:Wingdings;
panose-1:5 0 0 0 0 0 0 0 0 0;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0cm;
margin-right:0cm;
margin-bottom:0cm;
margin-left:36.0pt;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Calibri",sans-serif;}
p.msonormal0, li.msonormal0, div.msonormal0
{mso-style-name:msonormal;
mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
span.EmailStyle18
{mso-style-type:personal;
font-family:"Calibri",sans-serif;
color:windowtext;}
span.EmailStyle19
{mso-style-type:personal-reply;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
/* List Definitions */
@list l0
{mso-list-id:1966617412;
mso-list-type:hybrid;
mso-list-template-ids:170158646 134807553 134807555 134807557 134807553 134807555 134807557 134807553 134807555 134807557;}
@list l0:level1
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:Symbol;}
@list l0:level2
{mso-level-number-format:bullet;
mso-level-text:o;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:"Courier New";}
@list l0:level3
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:Wingdings;}
@list l0:level4
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:Symbol;}
@list l0:level5
{mso-level-number-format:bullet;
mso-level-text:o;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:"Courier New";}
@list l0:level6
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:Wingdings;}
@list l0:level7
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:Symbol;}
@list l0:level8
{mso-level-number-format:bullet;
mso-level-text:o;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:"Courier New";}
@list l0:level9
{mso-level-number-format:bullet;
mso-level-text:;
mso-level-tab-stop:none;
mso-level-number-position:left;
text-indent:-18.0pt;
font-family:Wingdings;}
ol
{margin-bottom:0cm;}
ul
{margin-bottom:0cm;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-GB" link="#0563C1" vlink="#954F72">
<div class="WordSection1">
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Hi Keith, DTNers,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Just some additional considerations after digesting yesterday meeting considerations:<o:p></o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Wish to keep green standalone blocks (i.e., by removing the mixed colour way currently supported in LTP spec). Apart from
specific mission requirements that agencies may want to provide here, I see the following points of some value:<o:p></o:p></span>
<ul style="margin-top:0cm" type="circle">
<li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level2 lfo1"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Space unidirectional links prone to error could benefit from erasure coding implementation. In this case, erasure codes could
be combined to green blocks. Applying erasure coding directly to encap packets might theoretically still also be possible, but in my view a bit less effective since encap packets might have to merged together to have the minimum encoding block size and splitting
it into segments for the encoding part. These latter functions are already in my opinion intrinsically available with LTP.<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level2 lfo1"><span style="font-size:11.0pt;mso-fareast-language:EN-US">If we prefer to “replace” green blocks operation with BP running directly on top of encap, we have to pay attention on the
case of large bundle (say few MB) which would be mapped directly into encap packets. In the case some of the transfer frames in which encap packets are transmitted got lost, it can be that an entire encap packet will be also dropped. When the same happens
in the case of green block, we may lose a single LTP segment, with limited degradation to overall reception of info at application (provided that the application is still able to take advantage of what received even when some data is missing)<o:p></o:p></span></li></ul>
</li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Green block segments “interleaving”. Agreed the fact that the term interleaving is misleading and that we don’t need to specify
this in the book, I’m wondering whether this is something really needed also at implementation level given the fact that different priorities could be directly managed at datalink level by means of different VCs (for example).<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Extension header. As already recorded during the Fall meetings, I agree that whatever additional information of use from consumers
external to the LTP core could simply transported in dedicated (maybe small) LTP blocks. But what if someone wants to develop (e.g., for some specific missions or experimentation) some LTP protocol updates requiring some signalling (i.e., transported somehow
in the header)? In that case I think having an extension header could be of value. Moreover if we want to retain the security extensions (RFC5327), the extension header must be there.<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">My 0.02 cents to the discussion<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Best Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;mso-fareast-language:EN-US">Tomaso<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt">From:</span></b><span lang="EN-US" style="font-size:11.0pt"> SIS-DTN <sis-dtn-bounces@mailman.ccsds.org>
<b>On Behalf Of </b>Dr. Keith L Scott<br>
<b>Sent:</b> Mittwoch, 10. Februar 2021 16:13<br>
<b>To:</b> sis-dtn@mailman.ccsds.org<br>
<b>Subject:</b> [Sis-dtn] SIS-DTN Telecon Today: LTP Discussion<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt">All,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt">I’d like to continue our LTP discussion from the Fall meetings and start working towards nailing down the set of changes we’d like to make. To that end, I’ve collected the proposed changes from
October into the attached spreadsheet. What I’d like to do today is to run through this, figure out what I’ve left out, and start building consensus around particular choices. We can iterate these discussions over email, and I’d LIKE to get most / all of
them nailed down by the next meetings in May.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt"> v/r,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt"> --keith<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:14.0pt"><o:p> </o:p></span></p>
</div>
</body>
</html>