openvpn speeds

[mcelio]

I have two eBoxes acting as routers in two locations. I have an OpenVPN tunnel set up between the two using TCP and port 51194, encryption is on by default in eBox as I understand.

I am experiencing slow speeds pulling files from a windows server in site 1 to a workstation in site 2. I can achieve much faster speeds sending files from site 2 to site 1. Both sites have 5 Mbps down and 1.5 Mbps up though they are not through the same provider.

I have compared the speeds of transfering files from site 1 to site 2 using FTP and VPN.
VPN - 30 KB/s       FTP - 200 KB/s

Transferring a file from site 2 to the server in site 1 I get speeds upwards of 120 KB/s.

I understand there is some overhead using VPN, but I am only getting about 20% of my maximum site 1 upload speed. Is there anything to tweak OpenVPN or ebox to help me get better performance? A different port number, UDP vs TCP? Can my provider (Timewarner) somehow be throttling the VPN traffic? Turning off encryption is not a possible solution.

[javi]

Hi,

Make sure you don't have installed the traffic shaping module or if you do, make sure it's disabled.

I would try with another port and UDP.

Yes, it's possible that your provider is throttling the traffic. I've seen really funny things such as this when dealing with openVPN and ISPs.

Keep us posted

[jcanfield]

Sounds like it could be a CPU issue, openVPN can chew up the resources, especially on older CPU's.  What do you have for processing at each end?

[mcelio]

I am trying to change the existing VPN config to UDP but it is not taking. The status still shows TCP after trying to save the change. Is there a problem with switching the protocols on an existing VPN config?

I do not have any traffic shaping modules (unless they are on by default).

Each of the routers/eBox machines are new with 1 Gb ram and 3.4 GHz P4's. The only modules I have enabled are network, firewall and OpenVPN. They are not acting as a proxy either.

[mcelio]

I checked the system resources while transferring files over the VPN tunnel. There is barely a blip in the CPU or RAM usage.

I had to create a new VPN connection because I couldn't change the existing one to UDP.

With the VPN tunnel using UDP I am getting much faster speeds (150KB/s), almost 80% of my upload speed at site A.

Is there a way to perhaps lower the encryption to achieve even higher transfer speeds?