NTT/ChinaTelCom troubleshooting

Our connectivity from the US to ChinaTelCom has been in the toilet for 2
months. The Olympics are over, and I'm assured by my Shanghai contacts that
The Great Firewall of China has been relaxed, yet the problem remains.
Local loops on each end test fine to other localized ip space. Symptoms
include large-email delivery delays/failures, large file transfer failures.
Firewalls and VPNs have been reviewed, NOCS have been contacted.
Fingerpointing is raging at its finest.

US endpoint is AS7358

Transit is AS2914

CN endpoint is AS4134

If there is anyone from those three networks who can help us figure out why
large packets are dropping on transmits from the US to CN, I would really
appreciate an off-list reply. Heck, I'll take any replies from anyone that
might have some inside information or similar experiences, or give me some
ideas on the best way to do some external black-hole router/mtu munging
detective work on these networks.



Many thanks to all the replies and help. There are some star performers
working for NTT, kudos to them for their professionalism and brainpower.

Follow-up question:
We've seen great improvement by testing throughput using
ChinaNetworkCommunications, AS4837. Before we switch service, does anyone
have experience with their network/service/administration?