<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<br>
<br>
<div class="moz-cite-prefix">On 9/29/21 04:23, PAUL R BARFORD wrote:<br>
</div>
<blockquote type="cite"
cite="mid:DM6PR06MB40597A22A0C759058C718E6782A99@DM6PR06MB4059.namprd06.prod.outlook.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<style type="text/css" style="display:none;">P {margin-top:0;margin-bottom:0;}</style>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif;
font-size: 12pt; color: rgb(0, 0, 0);"> <span
style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><span style="margin:0px;font-family:Calibri,
Helvetica, sans-serif">Hello,</span></span>
<div style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><br>
</div>
<div style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><span style="margin:0px;font-family:Calibri,
Helvetica, sans-serif">I am a researcher at the University
of Wisconsin. My colleagues at Northwestern University and
I are studying submarine cable infrastructure.</span></div>
<div style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><br>
</div>
<div style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><span style="margin:0px;font-family:Calibri,
Helvetica, sans-serif;color:rgb(34, 34,
34);background-color:rgb(255, 255, 255);display:inline
!important">Our interest is in identifying submarine links
in traceroute measurements. Specifically, for a given
end-to-end traceroute measurement, we would like to be able
to identify when two hops are separated by a submarine
cable. Our initial focus has been on inter-hop latency,
which can expose long links. The challenge is that
terrestrial long-haul links may have the same or longer link
latencies as short submarine links. So, we're interested in
whether there may be other features (e.g., persistent
congestion, naming conventions in router interfaces, peering
details, etc.) or techniques that would indicate submarine
links. </span></div>
<div style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><span style="margin:0px;font-family:Calibri,
Helvetica, sans-serif;color:rgb(34, 34,
34);background-color:rgb(255, 255, 255);display:inline
!important"><br>
</span></div>
<div style="margin:0px;font-size:12pt;background-color:rgb(255,
255, 255)"><span style="margin:0px;font-family:Calibri,
Helvetica, sans-serif;color:rgb(34, 34,
34);background-color:rgb(255, 255, 255);display:inline
!important">Any thoughts or insights you might have would be
greatly appreciated - off-list responses are welcome.</span><br>
</div>
</div>
</blockquote>
<br>
Back in the day, when submarine cables were not as rife, it was not
uncommon to see things like "FLAG" or "APCN-2" or "SMW-3" in
traceroutes. I haven't seen such in a very long time, but likely
some operators may still do this.<br>
<br>
For traceroutes that cross oceans visibly, e.g., lhr-jfk, mrs-mba,
hnd-lax, mru - cdg, e.t.c., you could glean from there. But many
operators do not follow any "common norm" to annotate things like
this, so YMMV.<br>
<br>
You also find some countries that will use a submarine festoon
either as a primary or backup route for a terrestrial link. In such
cases, the distances may be the same, or even shorter across the
festoon, e.g., consider a festoon cable between Cape Town - Durban,
vs. a land-based run for the same two points.<br>
<br>
Considering how wide-spread submarine links are for both short and
long spans, I think folk are simply treating them as any other link,
from an operational perspective. You may be able to come up with a
semi-automatic mechanism to measure this, but I fear without
deliberate and consistent human intervention, the data could get
stale very quickly.<br>
<br>
Mark.<br>
</body>
</html>