RE: China’s Slow Transnational Network

[David Guo via NANOG <nanog () nanog org>]

Hi Pengxiong,

The largest ISP in China, China Telecom offers 3 types of their IP Transit service

1. Normal China Telecom (AS4134), poor quality because of overselling their bandwidith.
2. CN2 GT (AS4809)
3. CN2 GIA (AS4809)

CN2 GT (Global Transit) is cheaper than CN2 GIA (Global Internet Access), CN2 GIA is the most expensive but with stable 
and best network quality.

Have you tested all of these 3 types? According to your pdf, only Alibaba Cloud in Hong Kong and Singapore has CN2 
connectivity.

Another reason is the population of China, which is around 1.4 billion, and only 3 major ISPs (CT, CU and CM) can offer 
service to home users in China.

Regards,

David

From: NANOG <nanog-bounces () nanog org> On Behalf Of Pengxiong Zhu
Sent: Tuesday, March 3, 2020 6:55 AM
To: Compton, Rich A <Rich.Compton () charter com>
Cc: North American Network Operators' Group <nanog () nanog org>; Zhiyun Qian <zhiyunq () cs ucr edu>
Subject: Re: China’s Slow Transnational Network

DDoS traffic is coming from China to the outside world, which should saturate the upstream link of China, however, what 
we observed is that the upstream link has high and stable performance, while the downstream link of China, which is 
traffic coming from the outside world to China, is suffering from slow speed.

Best,
Pengxiong Zhu
Department of Computer Science and Engineering
University of California, Riverside


On Mon, Mar 2, 2020 at 8:11 AM Compton, Rich A <Rich.Compton () charter com<mailto:Rich.Compton () charter com>> wrote:
My guess is that it’s all the DDoS traffic coming from China saturating the links.

From: NANOG Email List <nanog-bounces () nanog org<mailto:nanog-bounces () nanog org>> on behalf of Pengxiong Zhu 
<pzhu011 () ucr edu<mailto:pzhu011 () ucr edu>>
Date: Monday, March 2, 2020 at 8:58 AM
To: NANOG list <nanog () nanog org<mailto:nanog () nanog org>>
Cc: Zhiyun Qian <zhiyunq () cs ucr edu<mailto:zhiyunq () cs ucr edu>>
Subject: China’s Slow Transnational Network

Hi all,

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
interesting findings.

We find China's transnational networks have extremely poor performance when accessing foreign sites, where the 
throughput is often persistently
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).

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.



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.

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.
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.

Here is the link to our paper:
https://www.cs.ucr.edu/~zhiyunq/pub/sigmetrics20_slowdown.pdf

We appreciate any comments or feedback.
--

Best,
Pengxiong Zhu
Department of Computer Science and Engineering
University of California, Riverside
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