There are three main carriers into China. China Telecom (CT), China Unicom (CU) and China Mobile (CM). Each one of them runs their intl connectivity hot during peak hours (they buy from a number of other carriers): in both directions and DDoS is part of that. They're slow to upgrade and when they do it fills up fast. That said, the China GFW runs even hotter. There are several GFW complexes in China that the govt runs and each carrier has to run circuits thru them and give access to the govt to login and config mode to the routers that surround the GFW middle boxes (which are Huawei or ZTE boxes). The govt steer specific IP prefixes/subnets to diff fws due to the fact that they can't store all the rules on every box within that layer. The GFW is the biggest bottleneck as the govt upgrades them maybe twice a year. I've seen it run hot for 16+ hours a day in certain cities.
This is quite true. About a decade ago GFW was a simple IDS that occasionally sent RST packets down the pipes. Nowadays it's much more complicated. I've witnessed the GFW upgrade in process several times in which they default to drop every cross border connection over port 80 but allow everything else through, then gradually going back to normal one route at a time.
However I'm not sure if the GFW is the blame for every case of passive throttling. Certain provinces have it better than others and there is no obvious pattern, especially CMCC which constantly have issues connecting to domestic services, but otherwise has very little throttling once you know how to get past the GFW. The same cannot be said for other providers which throttles home users extra hard so their capacity can be sold to business customers.
The RST cannons still exist and they usually offload that in the domestic China networks to take the load off the GFW. The operators have to pay for them, though :(
As for the GFWs tactics they've certainly expanded things into jacking with TLS in addition to a few other things.
Nice to meet another person who struggles with China and knows what they're talking about and doesn't spread fud like most of the people I deal with on a regular basis.
