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Hello Nick,</div>
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I've added my collaborators to this reply - Esteban can comment on your observation re. Telia.</div>
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TTL <b>is</b> decremented on the paths we're analyzing. What we're curious about is why we're seeing a concentration of hops at a small number of routers that appear on international paths. I expected that when we looked at paths between e.g., US-Asia, US-Europe,
US-South America (considering measurements from Ark nodes doing traceroutes to/from those locations), we would see the first instances of routers located the US along the west coast, east coast and south coast respectively. We did not expect to see Chicago
as a first hop location in the US and are wondering e.g., if large providers do this to simplify their operations. Hopefully that makes sense. Any further thoughts are appreciated.</div>
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Regards, PB</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Nick Hilliard <nick@foobar.org><br>
<b>Sent:</b> Monday, January 17, 2022 12:36 PM<br>
<b>To:</b> PAUL R BARFORD <pb@cs.wisc.edu><br>
<b>Cc:</b> nanog@nanog.org <nanog@nanog.org><br>
<b>Subject:</b> Re: Long hops on international paths</font>
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<div class="PlainText">PAUL R BARFORD wrote on 17/01/2022 18:02:<br>
> For example, there is a router operated by Telia (AS1299) in Chicago <br>
> that has a high concentration of such links.<br>
<br>
this doesn't appear to match 1299's public network topology:<br>
<br>
<a href="https://www.teliacarrier.com/our-network.html">https://www.teliacarrier.com/our-network.html</a><br>
<br>
Is ttl decrement disabled on the test paths you're measuring?<br>
<br>
Broadly speaking, if you have a point-to-point link from one location to <br>
another (or parallel set of links with a common failure path, e.g. waves <br>
on a specific fibre path), there's a single router at each end.<br>
<br>
Nick<br>
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