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<font color="#0000FF">At 01:37 PM 2/9/2007, Dave Israel wrote:<br>
<blockquote type=cite class=cite cite="">I think the question is still
"Why are we debating the link layer again when people are still not
convinced that there is value in basic networking in the first
place?"</font></blockquote><br>
Dave: we are discussing the Link layer precisely because of that very
point. Namely, a very large number of people across the international
community simply aren't buying into the basic need for networking in
space.<br><br>
The whole reason for raising this issue again was to point out that the
real world is rarely black and white. Individuals who bloviate about the
immaculate properties of black or the divine nature of white are
unhelpful. They polarize opinion and they turn off the vast majority of
people who see the shades of gray. The real world of space missions is
populated mainly by pragmatic and conservative engineers who will accept
change when they are convinced of the need for change, not because some
self-appointed guru lectures them that it will be good for their
souls.<br><br>
One way that you convince people to migrate from black to white is to
offer hybrid solutions that allow them to transition through gray in an
evolutionary manner. The Link layer is important because it needs to
facilitate such evolution. We have existing CCSDS Link layers that can
equally well support black, white or gray traffic. They are layered, they
are robust, they were specifically designed for space mission use, they
are well understood, they are extensively used, they are well supported
by industry and they are agnostic to the technologies above them. They
can handle bitstreams or octet streams or TDM or Ethernet frames or Space
Packets or IPv4 or IPv6 or ISO-8473 or LTP/DTN or whatever - all mixed
together on a single Physical channel if desired - and they simply don't
care.<br><br>
The case for basic networking is almost certainly going to be made in the
international community by offering people an evolutionary path. The
existing CCSDS Link layers are the platforms on which the CCSDS Cislunar
working group in the CCSDS Space Internetworking Services Area is going
to build its case. End of subject. If people want to propose new Link
layers, they can make their separate cases to the CCSDS Space Link
Services Area Director.<br><br>
Best regards<br>
Adrian<br>
<x-sigsep><p></x-sigsep>
Adrian J. Hooke<br>
Chairman, CCSDS Engineering Steering Group (CESG)</body>
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