slow speeds from new york to shanghai

We are getting poor performance with a VPN from our main site in New York to a branch in Shanghai. We have a 50Mbps link in New York and a 30 Mbps link in Shanghai. however we only get about 500kbps. Is there anyway that we can improve this short of getting a guaranteed link between the two offices?
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ryan80Asked:
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JohnBusiness Consultant (Owner)Commented:
Don't forget that VPN is going in the upload direction for half its packets. So VPN will be no faster than the slowest upload speed. Check and see what that is.

Also, the default MTU in the router for these installations is 1500. VPN works best at 1492 or even a tad slower. This reduces overall packet fragmentation. Check both ends for MTU.

... Thinkpads_User
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ryan80Author Commented:
That was one of the things that i was thinging about. I know that the MTU is set to 1500. I will try reducing it and see what I get as a result.

We get 30 over 30 dedicated at the lesser site. When we test it to a local location we usually get about 80% of what it is rated at for upload. Even if it was 50% we should still be getting better speeds.
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John MeggersNetwork ArchitectCommented:
+1 on the MTU size.  Excessive fragmentation because of MTU size is a typical issue with IPSec.
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ryan80Author Commented:
The VPN is between to Cisco ASA's, so should the MTU be changed on the inside or outside interface?
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JohnBusiness Consultant (Owner)Commented:
The MTU that will affect the VPN is on the inside interface.   ... Thinkpads_User
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JohnBusiness Consultant (Owner)Commented:
Thank you. I was happy to assist and trust speeds are better now. ... Thinkpads_User
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