<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:st1="urn:schemas-microsoft-com:office:smarttags" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 11 (filtered medium)">
<!--[if !mso]>
<style>
v\:* {behavior:url(#default#VML);}
o\:* {behavior:url(#default#VML);}
w\:* {behavior:url(#default#VML);}
.shape {behavior:url(#default#VML);}
</style>
<![endif]-->
<title>Re: [Sis-csi] RE: networking details</title>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="PlaceType"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="PlaceName"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="PostalCode"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="State"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="Street"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="City"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="address"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="place"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="country-region"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="time"/>
<o:SmartTagType namespaceuri="urn:schemas-microsoft-com:office:smarttags"
name="date"/>
<!--[if !mso]>
<style>
st1\:*{behavior:url(#default#ieooui) }
</style>
<![endif]-->
<style>
<!--
/* Font Definitions */
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-reply;
font-family:Arial;
color:navy;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.25in 1.0in 1.25in;}
div.Section1
{page:Section1;}
-->
</style>
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Ed<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Good comments. Add to that the fact that
bandwidth becomes more critical the closer you get to the sensor/effector. VCs
were invented to keep the overhead down. IPv4/v6 pale in comparison when it
comes to bandwidth utilization. Said another way, do you want to use the limited
bandwidth for data or for sophisticated routing mechanisms?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> sis-csi-bounces@mailman.ccsds.org
[mailto:sis-csi-bounces@mailman.ccsds.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Edward Greenberg<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, <st1:date Year="2007"
Day="09" Month="2" ls="trans" w:st="on">February 09, 2007</st1:date> <st1:time
Minute="27" Hour="15" w:st="on">3:27 PM</st1:time><br>
<b><span style='font-weight:bold'>To:</span></b> Dave Israel<br>
<b><span style='font-weight:bold'>Cc:</span></b> Keith Hogie; CCSDS Cislunar
Space Internetworking WG<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Sis-csi] RE:
networking details</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Dave, You are correct and this stuff that is flying around
is just religious ferver. I have been trying to get a picture of
the in space networking needs for Constellation for a long time and have yet to
see anything that is operationally blessed. We can talk about routing
desires for ever but what are the real requirements. Are things going to
take random walks in space or are missions and hardware movements going to
scheduled and exhaustively tested before anything moves. Is automated
address management needed, or is it over kill for the first 30 years of the
program? And If the environment in the later years of the
program is centered around the Moon or Mars, how will the delays effect the
operational use of UDP. Deep space missions have been forced to use store
and forward operations for years, and the protocols supporting those missions
are focus for that environment. So can anyone supply an operational
scenario that requires the advanced networking features that IPv6 brings to the
table. <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>At <st1:time Minute="40" Hour="14" w:st="on">2:40 PM</st1:time> -0500 <st1:date
Year="07" Day="9" Month="2" ls="trans" w:st="on">2/9/07</st1:date>, Dave Israel
wrote:<o:p></o:p></span></font></p>
</div>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Before another whole thread starts about link layer issues again, can
somebody explain why the link layer matters are so critical at this time that
we keep spending time and energy debating them, instead of working on the many
networking issues that need to be resolved? I'd rather see that
discussed, than any arguments about any link protocols.<br>
<br>
It seems to me that the real need is to get missions to start evolving to
networking based communications first. Once that starts, optimization may
follow. How much time have we lost in "IP<i><span style='font-style:
italic'> versus</span></i> CCSDS" debates, when in reality there really
isn't mutually exclusive decision required?<br>
<br>
Dave<br>
<br>
At 02:20 PM <st1:date Year="2007" Day="9" Month="2" ls="trans" w:st="on">2/9/2007</st1:date>,
Keith Hogie wrote:<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><st1:City w:st="on"><st1:place w:st="on"><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>Adrian</span></font></st1:place></st1:City>,<br>
<br>
A major concern is what you mentioned below about Virtual Channels.<br>
Those are a CCSDS data format that was developed 20 years ago and was<br>
a fine solution for the time. It sounds like you are proposing that<br>
that VC data structure be maintained as the underlying format for civil<br>
space programs for the next 20 years. Does it make sense to<br>
plan on extending the life of a 20 year old protocol format for<br>
20 more years or is it time for an upgrade or replacement of<br>
the VC format.<br>
<br>
During the last 20 years lots of protocols have come and gone and<br>
been replaced by new ones that better suit users current needs. The<br>
commercial world primarily uses Frame Relay and DVB over thousands of satellite
links supporting tens of thousands of users. They have<br>
created a very large commercial market of internationally<br>
interoperable products with much better layering and function<br>
support than the basic CCSDS VCDU.<br>
<br>
So it seems that a major question is whether the current VC<br>
structure is the best structure to use for the future or is it<br>
time to upgrade to more current solutions at that level?<br>
<br>
As far as future IP missions interoperating with future missions<br>
that see no need for IP, that's fine but then they don't have any<br>
plans to communicate with future IP missions anyway. Ground stations<br>
can still support both IP and non-IP formats as many do already.<br>
The facilities, antennas, transmitters, and receivers still need<br>
to do their jobs just the same. The real question is whether the<br>
bits coming off the space link go into a CCSDS specific box that<br>
processes VCs or if the bits go into a commercial router. This<br>
is not a major change to the infrastructure. Yes, it is a change,<br>
but the communication world has changed drastically over the last<br>
20 years and we need to decide if it is time for the civil space<br>
community to catch up or if it wants to keep doing its own thing.<br>
<br>
Keith<br>
<br>
<br>
Adrian J. Hooke wrote:<br>
<br>
<o:p></o:p></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Maybe this is a good time to take stock of where we are. I think that
it is fair to say that there is broad international agreement that:<br>
1. We can see future requirements for the emergence of a more networked
approach to space communications.<o:p></o:p></span></font></p>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>2. Accordingly, we need to develop a migration strategy that leads us
towards more capable networking protocols.<br>
3. IP has a role in that migration strategy.<br>
Beyond those elements of consensus, it's not clear that there is much agreement
on how or when to initiate change.<br>
At 06:09 AM <st1:date Year="2007" Day="8" Month="2" ls="trans" w:st="on">2/8/2007</st1:date>,
Keith Hogie wrote:<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> Moving to spacecraft using Internet protocols a change to the
whole space communication concept.<o:p></o:p></span></font></p>
</blockquote>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
snip<br>
<br>
<o:p></o:p></span></font></p>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>If we start launching some of our future systems with no routed IP, is
there a clean path for them to "migrate" and be full participants in
the future network.<o:p></o:p></span></font></p>
</blockquote>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>Turn that around. If we start launching *some* of our future systems
exclusively with routed IP, is there a clean path for them to be full
participants in the future international community of missions that see no need
for it?<br>
Nobody's arguing that there won't be an increasing need for portions of the
international space mission support infrastructure to adopt more powerful
routing technologies. When you need IP and IP works, you should use IP. But
does that mean that *everything* has to become IP-based, all at once? And yes,
there's a migration path: it's called international space standardization in
general and in particular it's called a Virtual Channel. It means that you can
run part of your system using existing infrastructure, in parallel with part of
your system using IP-based approaches. Change the mix of traffic on the VCs and
you can migrate with hardly any impact.<o:p></o:p></span></font></p>
</blockquote>
</blockquote>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
----------------------------------------------------------------------<br>
Keith Hogie
e-mail: Keith.Hogie@gsfc.nasa.gov<br>
Computer Sciences Corp. office:
301-794-2999 fax: 301-794-9480<br>
<st1:Street w:st="on"><st1:address w:st="on">7700 Hubble Dr</st1:address></st1:Street>.<br>
<st1:place w:st="on"><st1:City w:st="on">Lanham-Seabrook</st1:City>, <st1:State
w:st="on">MD</st1:State> <st1:PostalCode w:st="on">20706</st1:PostalCode>
<st1:country-region w:st="on">USA</st1:country-region></st1:place>
301-286-3203 @ NASA/Goddard<br>
----------------------------------------------------------------------<br>
<br>
_______________________________________________<br>
Sis-CSI mailing list<br>
Sis-CSI@mailman.ccsds.org<br>
http://mailman.ccsds.org/cgi-bin/mailman/listinfo/sis-csi<o:p></o:p></span></font></p>
</blockquote>
</blockquote>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>______________________________________________________________<br>
Dave Israel<br>
Leader, Advanced Technology Development Group<br>
Microwave & Communication Systems Branch<br>
<st1:place w:st="on"><st1:PlaceName w:st="on">NASA</st1:PlaceName> <st1:PlaceName
w:st="on">Goddard</st1:PlaceName> <st1:PlaceName w:st="on">Space</st1:PlaceName>
<st1:PlaceName w:st="on">Flight</st1:PlaceName> <st1:PlaceType w:st="on">Center</st1:PlaceType></st1:place>
Code 567.3<br>
<st1:place w:st="on"><st1:City w:st="on">Greenbelt</st1:City>, <st1:State
w:st="on">MD</st1:State> <st1:PostalCode w:st="on">20771</st1:PostalCode></st1:place><br>
Phone: (301) 286-5294 Fax: (301)
286-1769<br>
E-mail: dave.israel@nasa.gov<br>
<br>
"Without deviation from the norm, progress is not possible."
-Frank Zappa<o:p></o:p></span></font></p>
</blockquote>
<blockquote style='margin-top:5.0pt;margin-bottom:5.0pt' type=cite cite>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
_______________________________________________<br>
Sis-CSI mailing list<br>
Sis-CSI@mailman.ccsds.org<br>
http://mailman.ccsds.org/cgi-bin/mailman/listinfo/sis-csi<o:p></o:p></span></font></p>
</blockquote>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
</div>
</body>
</html>