OpenVPN Support Forum

Hi,

I configure a bridge with openvpn but the bandwith is limited to 10Mb with a tap device.
I do some several test (CPU with aesni engine, ...) but the bandwith stay at 10 Mb.

I search a solution in the forom to increase the bandwith but I found nothing.

My network cards are in Gb and I don't need routing (so no tun device).

Is it possible to change the speed of the tap device or do someone have any solution to increase the bandwith with openvpn and a bridge.

Thanks for your help.

the 10 Mbps network speed of the tap device (on windows) is bogus - the actual speed of the device can be much higher.
On Windows and in bridged mode I won't expect you to get much more than 100 Mbps, however. If you don't need bridging then don't use.

Currently there seems to be an upper limit to the speed of an OpenVPN tunnel of ~ 340 Mbps (tun or tap). This is due to way packet flow through the system, even without encryption or compression.

Sorry for my late answer... and thank you for your response.

I m using gentoo for my openvpn tunnels. I have performance of 300Mbps with tun device and cryptography.

I need a bridge and would like some security in this bridge.
So I choose Openvpn because I am using it since a long time.
But a bridge need a Tap device and it appears that he is limited to 10 Mbps (ethtool tap0). I make test with Iperf I have a bandwith of 10Mbps. It look like it is blocked. The cpu ressource are good.

When I make a bridge (brctl add, ...) without Openvpn I have a bandwith of 1Gbps but no security.

So is there any solution to increase the speed of the tap device?

Bruno

running 'ethtool' on a tap device is bound to give bogus results ; it's likely that the tap device is not returning a sensible answer for the speed and hence 'ethtool' will display 10Mbps.

You should be able to get more than 10 Mbps out of a bridged setup , but this depends a lot on the network setup and system parameters. Try playing with the --fragment and --mss-fix options.

Thanks Jan,

I will try it and give the results.