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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>From an industrial process control systems
perspective, IP is used at the supervisory level, but not at the control level.
The reasoning is clear. First, control systems have limited interconnectivity –
just enough to do its job. Second, control systems don’t want external
communcations to have the potential for disrupting control. Therefore, gateways
are used connect control networks to supervisory networks. In reality, there is
usually more than one layer of supervisory networks, isolated from each other
by gateways. For cost reasons, almost all supervisory networks use IP, but with
private subnet addresses. Private subnet addresses ensure that there are no unregulated
cross network traffic flows.<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>
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<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>Assi Friedman<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, <st1:date
Year="2007" Day="08" Month="2" ls="trans" w:st="on">February 08, 2007</st1:date>
<st1:time Minute="04" Hour="14" w:st="on">2:04 PM</st1:time><br>
<b><span style='font-weight:bold'>To:</span></b> 'Adrian J. Hooke'; '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>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>I would like to point out that a lot of
discussion needs to go into the physical/link layers of this migration. CCSDS
as-is is has its history significantly influenced from the STDN era. This
history does not make it very conducive to IP in space. Migrating to IP will
require us to address the physical/link layers. As is, CCSDS had the foresight
to acknowledge that there will be a future need to readdress this, but the
future is now present. I try to start at the side closest to the hardware,
since protocol stacks can be reloaded, hardware boxes are much harder to
reload.<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'>Assi<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>
<p><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'>****************************</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'> Assi Friedman - Innoflight Inc.</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'> 5850 Oberlin Dr. Suite 340</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'> San Diego, CA 92121</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'> Tel: (858) 638-1580 X13</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'> Fax: (858) 638-1581</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'> Email: afriedman@innoflight.com</span></font><font
color=navy><span style='color:navy'> <br>
</span></font><font size=2 color=navy face=Verdana><span style='font-size:10.0pt;
font-family:Verdana;color:navy'>****************************</span></font><font
color=navy><span style='color:navy'> </span></font><o:p></o:p></p>
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<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>Adrian J. Hooke<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, <st1:date
Year="2007" Day="08" Month="2" ls="trans" w:st="on">February 08, 2007</st1:date>
<st1:time Minute="34" Hour="11" w:st="on">11:34 AM</st1:time><br>
<b><span style='font-weight:bold'>To:</span></b> 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>
<p class=MsoNormal style='margin-bottom:12.0pt'><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>
<br>
1. We can see future requirements for the emergence of a more networked
approach to space communications.<br>
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>
<br>
Beyond those elements of consensus, it's not clear that there is much agreement
on how or when to initiate change. <br>
<br>
<font color=blue><span style='color:blue'>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:<o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'> Moving to spacecraft using Internet
protocols a change to the whole space communication concept.</span></font>
<o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
No, it's not a change to the space communication *concept*; it's a change to
the space communication *infrastructure*. If we go there in one big bang, it
will certainly change a lot of infrastructure. But is it change for the sake of
change, or change because we simply can't operate another day in space without
an all-IP system?<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>Now we are changing the space end so that
selected Internet technologies and be used end-to-end.</span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
Why? There are plenty of cases where selected use of Internet technologies is
beneficial *without* using them end-to-end.<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>If we accept that we want and need a routed
infrastructure in space in the future, why wouldn't we want to start putting it
in place with missions currently being built.</span></font> <o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
Well, cost ands risk *might* be among the reasons. Why do the NASA Exploration
vehicles currently being built look so much like Apollo?<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>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. </span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
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>
<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.<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>Isn't it more beneficial to take this
opportunity to deploy a whole fleet of new systems and start the first systems
with the technologies we want to end up with.</span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
This far out, how do you know where you will end up? Isn't it more beneficial
to take the opportunity to deploy new systems that are based on the
technologies that we use now, which already have the built-in capability to evolve
towards IP or any other future routed approach? <br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>Starting new missions with IP technologies
also means that they can start benefiting from the greatly increased options
for early testing between various subsystems. Systems don't need to wait until
final integration and test to start doing interoperability tests. With IP
interfaces built in, systems can start running basic interface and
functionality tests while they are still at their manufacturing
locations. This can be done years earlier than normal I&T and find<br>
basic problems much earlier when they are easier and cheaper to fix. </span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
This claim is so sweeping that it deserves its own discussion thread. Suffice
to say that there are many people on this list who strongly doubt that the
impacts on the real world of space mission I&T are anywhere near that rosy.<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>I agree that we don't need to pin down all
the details now, but we do need to have some sort of plan on how things will
roll out. </span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
We all agree with that.<br>
<br>
<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=blue face="Times New Roman"><span
style='font-size:12.0pt;color:blue'>We may not need all the network routing
capabilities for 10 years but there seem to be lots of benefits from starting
to make use of end-to-end Internet technologies now.</span></font><o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'><br>
Of course: that's why we formed this Cislunar Space Internetworking working
group. But as an international standardization working group, it should develop
a pragmatic and consensus strategy for how it proposes to move the
international space community forward. We need a clear picture - agreed by all
partners - that shows why we need to change, when we need to change and how we
need to change.<br>
<br>
///adrian<o:p></o:p></span></font></p>
<p></x-sigsep><font size=3 face="Times New Roman"><span style='font-size:12.0pt'><x-sigsep>Adrian
J. Hooke<br>
Chairman, CCSDS Engineering Steering Group (CESG)<o:p></o:p></span></font></p>
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