<html>
<body>
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="#0000FF">At 06:09 AM 2/8/2007, Keith Hogie wrote:<br>
<blockquote type=cite class=cite cite=""> Moving to spacecraft
using Internet protocols a change to the whole space communication
concept.</font> </blockquote><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>
<blockquote type=cite class=cite cite=""><font color="#0000FF">Now we are
changing the space end so that selected Internet technologies and be used
end-to-end.</font></blockquote><br>
Why? There are plenty of cases where selected use of Internet
technologies is beneficial *without* using them end-to-end.<br><br>
<blockquote type=cite class=cite cite=""><font color="#0000FF">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.</font> </blockquote><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>
<blockquote type=cite class=cite cite=""><font color="#0000FF">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. </font></blockquote><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>
<blockquote type=cite class=cite cite=""><font color="#0000FF">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.</font></blockquote><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>
<blockquote type=cite class=cite cite=""><font color="#0000FF">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.
</font></blockquote><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>
<blockquote type=cite class=cite cite=""><font color="#0000FF">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.
</font></blockquote><br>
We all agree with that.<br><br>
<blockquote type=cite class=cite cite=""><font color="#0000FF">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.</font></blockquote><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<br>
<x-sigsep><p></x-sigsep>
Adrian J. Hooke<br>
Chairman, CCSDS Engineering Steering Group (CESG)<br>
</body>
</html>