Large File Syncing Not Reaching Expected Speed

[pro-p2p]

Hello:

 

I have recently installed BTSync (1.4.x) on two Ubuntu servers. I'm trying to sync one folder with only a few (less than 100) large files (100 Megabytes or more), that don't change much, over a great geographical distance. I was hoping the UDP protocol that BTSync uses would increase transfer speeds, but transfers are slower than TCP (via secure webdav) -- I'm topping out around 5 megabits per second. With iperf I can test UDP up to about 17 megabits in the most challenged direction between these two machines.

 

Both servers use a specified UDP port for BTSync and are behind 1:1 NAT with that specified port allowed incoming. The firewalls do not block outbound connections. On both routers I can see (looking at the state table) that the UDP port I chose for each is open (with no port translation) and the two machines are in contact with each other. I'm trying to do this with the peers specified, not using the tracker, and other than poor speed, BTSync is working correctly.

 

Have I missed anything that could be killing my speed? Is it ISPs recognising 'Bittorrent' being used and slowing the speed somewhere along the line? If so, how best to defeat that?

 

Thanks for your help.