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<p>Hi, <br>
</p>
<pre wrap="">>> Does anybody have more or less recent data on the average, median and maximum diameter (ip hop count) of the Internet?
</pre>
First, to give some hints regarding the initial question: A year ago
I did some analysis based on Caida's routed /24 topology data set
(<a class="moz-txt-link-freetext" href="https://www.caida.org/data/active/ipv4_routed_24_topology_dataset.xml">https://www.caida.org/data/active/ipv4_routed_24_topology_dataset.xml</a>)
for data at the beginning of Jan. 2015. Its not using all available
data but rather only traceroutes that reached the destination. The
attached figure shows violin plots for each day - vertically, they
show the distribution of Hopcounts (looks a little weird due to
Hopcounts only beeing Integers). <br>
<br>
However, please keep in mind: <br>
<br>
i.) the data set is collected from only few physical locations but
has traceroutes towards every routed /24 prefix. <br>
ii.) only a subset of the entire data set is shown.<br>
iii.) its from 2015. <br>
iv.) there is a good chance that it is not representative for the
"entire" Internet.<br>
<br>
<br>
<br>
Secondly, regarding the ongoing discussion: <br>
<br>
+1 for Tim's answer. IMHO, neither AS paths nor IP paths, in
general, are reliable proxies for e.g. latency or physical distance.
In addition, keep in mind that we are only able to observe a certain
part of the Internet and thus it's hard to make claims about the
"entire" Internet. <br>
<br>
best regards,<br>
Lars <br>
<br>
<div class="moz-cite-prefix">Am 22.11.18 um 10:55 schrieb
<a class="moz-txt-link-abbreviated" href="mailto:tim@pelican.org">tim@pelican.org</a>:<br>
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<blockquote type="cite"
cite="mid:1542880547.21228510@apps.rackspace.com">
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<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">On Thursday, 22 November,
2018 05:30, "William Herrin" <a class="moz-txt-link-rfc2396E" href="mailto:bill@herrin.us"><bill@herrin.us></a> said:</p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;"> </p>
<div id="SafeStyles1542879997">
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">> Good question! It
matters because a little over two decades ago we had<br>
> some angst as equipment configured to emit a TTL of 32
stopped being<br>
> able to reach everybody. Today we have a lot of
equipment configured<br>
> to emit a TTL of 64. It's the default in Linux, for
example. Are we<br>
> getting close to the limit where that will cause
problems? How close?<br>
<br>
</p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">If it's hop-count that's
interesting, I think that raises a question on the potential
for a sudden large change in the answer, potentially with
unforeseen consequences if we do have a lot of devices with
TTL=64.</p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;"> </p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">Imagine a "tier-1"
carrying some non-trivial fraction of Internet traffic who
is label-switching global table, with no TTL-propagation
into MPLS, and so looks like a single layer-3 hop today. In
response to traceroute-whingeing, they turn on
TTL-propagation, and suddenly look like 10 layer-3 hops.</p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;"> </p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">Having been in the
show/hide MPLS hops internal debate at more than one
employer, I'd expect flipping the switch to "show" to
generate a certain support load from people complaining that
they are now "more hops" away from something they care about
(although RTT, packet-loss, throughput remain exactly the
same). I wouldn't have expected to break connectivity for a
whole class of devices. </p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;"> </p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">Regards,</p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;">Tim.</p>
<p style="margin:0;padding:0;font-family: arial; font-size:
10pt; overflow-wrap: break-word;"> </p>
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