Did you compare CERNET with commodity networks? (My anecdotal observations from a couple years ago suggest that Internet2 to CERNET is very good when other paths are poor to unusable.)
--David Burns On Mon, Mar 2, 2020 at 7:58 AM Pengxiong Zhu <pzhu...@ucr.edu> wrote: > 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 >