<div dir="ltr"><br><div>FYI, </div><div><br></div><div>We are in the process of starting a new Working Group at IETF, Timer Variant Routing or TVR.</div><div><a href="https://datatracker.ietf.org/group/tvr/about/">https://datatracker.ietf.org/group/tvr/about/</a><br></div><div><br></div><div>Some of the uses cases are for space applications where you can predict or schedule the availability and capacity of "links" (radio, optical)</div><div><br></div><div>This gets sort of merged with DTN (Delay/Disruption Tolerant Networking.)</div><div><br></div><div>NASA GRC has developed a High Speed version of DTN aka HDTN that is being tested in terrestrial setups but soon to be tested in space.</div><div><a href="https://www1.grc.nasa.gov/space/scan/acs/tech-studies/dtn/">https://www1.grc.nasa.gov/space/scan/acs/tech-studies/dtn/</a><br></div><div><br></div><div>For now all this is experimental.</div><div><br></div><div>Plus there are several commercial entities also working in this realm, one is <a href="https://www.aalyria.com/">https://www.aalyria.com/</a>, spin-off of Google's Loon project.</div><div><br></div><div>-J<br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sun, Jan 22, 2023 at 5:17 PM Michael Thomas <<a href="mailto:mike@mtcc.com">mike@mtcc.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<div>On 1/22/23 3:05 PM, Matthew Petach
wrote:<br>
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<div dir="ltr" class="gmail_attr">On Sun, Jan 22, 2023 at 2:45
PM Michael Thomas <<a href="mailto:mike@mtcc.com" target="_blank">mike@mtcc.com</a>>
wrote:<br>
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<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">I read in the Economist
that the gen of starlink satellites will have <br>
the ability to route messages between each satellite. Would
conventional <br>
routing protocols be up to such a challenge? Or would it
have to be <br>
custom made for that problem? And since a lot of companies
and countries <br>
are getting on that action, it seems like fertile ground for
(bad) wheel <br>
reinvention?<br>
<br>
Mike<br>
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<div>Unlike most terrestrial links, the distances between
satellites are not fixed, </div>
<div>and thus the latency between nodes is variable, making
the concept of <br>
"Shortest Path First" calculation a much more dynamic and
challenging </div>
<div>one to keep current, as the latency along a path may be
constantly changing </div>
<div>as the satellite nodes move relative to each other,
without any link state actually</div>
<div>changing to trigger a new SPF calculation.</div>
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<p>One thing that is in their favor is that while they are moving,
they are moving in a predictable manner. It seems that each router
could, essentially, locally update routes until they are told
otherwise?<br>
</p>
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<div>I suspect a form of OLSR might be more advantageous in a
dynamic partial </div>
<div>mesh between satellites, but I haven't given it as much
deep thought as would </div>
<div>be necessary to form an informed opinion.</div>
<div><br>
</div>
<div>So, yes--it's likely the routing protocol used will not
be entirely "off-the-shelf" </div>
<div>but will instead incorporate continuous latency
information in the LSDB, </div>
<div>and path selection will be time-bound based on the rate
of increase in latency </div>
<div>along currently-selected edges in the graph.</div>
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<p>Has IETF looked at this, do you know? Even if the routers can't
interoperate with other systems, it would be good to have some
routing clue with a lot of eyeballs on it to not make rookie
mistakes.<br>
</p>
Mike<br>
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