On Mon, Mar 2, 2020 at 11:46 AM Pengxiong Zhu <pzhu011@ucr.edu> wrote:

Those are good insights. Our first guess is censorship too, and we discussed the possibilities of censorship side effects in Section 5.1 Censorship.

My guess is that it’s all the DDoS traffic coming from China saturating the links. 

 

In fact, Great Canon (GC) [55] is such an in-path system. But it is known for intercepting a subset of traffic (based on protocol type) only. What’s more, GC has been activated only twice in history (the last one in 2015 [55]). However, it might be the case that the in-path capability is re-purposed to perform general traffic throttling. If that is the case, they have done a good job because the throttling resembles natural congestion from the loss rate and latency point of view. The asymmetric performance between downstream and upstream traffic can be explained by the natural imbalance of transnational traffic (where the upstream traffic from China to outside is not significant enough to throttle).

Maybe... I dunno.... get rid of the Great Firewall of China?

What do you mean? Do you mean the slow traffic is to bypass the GFW or the slow traffic is caused by GFW? 

 

You've pretty much determined there is nothing we can do on this side of the Chinese mainland to improve throughput - the bottlenecks are all inside China.

As you noted, ~35% of the bottlenecks were GFW related.  I wonder how many retransmissions that results in, slowing everything down that much further? Until the mainland Chinese Government allows the free passage of information, there will be bottlenecks. And bottlenecks have a habit of affecting traffic flows outside of their own area. 

I doubt that any one thing is the source of the entire problem. But add them all together.... 

--

Jeff Shultz

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