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<p class="MsoNormal"><span style="font-size:12.0pt">My guess is that it’s all the DDoS traffic coming from China saturating the links.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">NANOG Email List <nanog-bounces@nanog.org> on behalf of Pengxiong Zhu <pzhu011@ucr.edu><br>
<b>Date: </b>Monday, March 2, 2020 at 8:58 AM<br>
<b>To: </b>NANOG list <nanog@nanog.org><br>
<b>Cc: </b>Zhiyun Qian <zhiyunq@cs.ucr.edu><br>
<b>Subject: </b>China’s Slow Transnational Network<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131">Hi all,<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131">We are a group of researchers at University of California, Riverside who have been working on measuring the transnational network performance (and have previously asked questions on the mailing list). Our work
has now led to a publication in Sigmetrics 2020 and we are eager to share some<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#313131">interesting findings. <o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131">We find China's transnational networks have extremely poor performance when accessing foreign sites, where the throughput is often persistently<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#313131">low (e.g., for the majority of the daytime). Compared to other countries we measured including both developed and developing, China's transnational network performance is among the worst (comparable and even
worse than some African countries).<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131">Measuring from more than 400 pairs of mainland China and foreign nodes over more than 53 days, our result shows when data transferring from foreign nodes to China, 79% of measured connections has throughput lower
than the 1Mbps, sometimes it is even much lower. The slow speed occurs only during certain times and forms a diurnal pattern that resembles congestion (irrespective of network protocol and content), please see the following figure. The diurnal pattern is fairly
stable, 80% to 95% of the transnational connections have a less than 3 hours standard deviation of the slowdown hours each day over the entire duration. However, the speed rises up from 1Mbps to 4Mbps in about half an hour.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131"><img id="_x0000_i1025" src="blob:null/71cf5a6a-3841-41ce-a1d4-207b59182189" alt="blob:null/71cf5a6a-3841-41ce-a1d4-207b59182189"><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131">We are able to confirm that high packet loss rates and delays are incurred in the foreign-to-China direction only. Moreover, the end-to-end loss rate could rise up to 40% during the slow period, with ~15% on
average.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#313131"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="color:#313131">There are a few things noteworthy regarding the phenomenon. First of all, all traffic types are treated equally, HTTP(S), VPN, etc., which means it is discriminating or differentiating any specific kinds of traffic.
Second, we found for 71% of connections, the bottleneck is located inside China (the second hop after entering China or further), which means that it is mostly unrelated to the transnational link itself (e.g., submarine cable). Yet we never observed any such
domestic traffic slowdowns within China.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#313131">Assuming this is due to congestion, it is unclear why the infrastructures within China that handles transnational traffic is not even capable to handle the capacity of transnational links, e.g., submarine cable,
which maybe the most expensive investment themselves.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:#313131">Here is the link to our paper:<o:p></o:p></span></p>
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<p class="MsoNormal"><a href="https://www.cs.ucr.edu/~zhiyunq/pub/sigmetrics20_slowdown.pdf" target="_blank">https://www.cs.ucr.edu/~zhiyunq/pub/sigmetrics20_slowdown.pdf</a><span style="color:#313131"><br>
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<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="color:#313131">We appreciate any comments or feedback. <o:p></o:p></span></p>
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<p class="MsoNormal">-- <o:p></o:p></p>
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<p class="MsoNormal"><br>
Best,<br>
Pengxiong Zhu<br>
Department of Computer Science and Engineering<br>
University of California, Riverside<o:p></o:p></p>
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