OpenVPN ethernet bridging gets capped

[jonnytabpni]

Hi folks,

I have an openvpn server running on a seperare machine behind my pfsense router. The openvpn client is in another country and is connected via a DSL connection (8Mbps down and 832kbps up). The openvpn server is running on a virtual machine (VMware ESXi).

I was orignally using openvpn routing and got good transfer speeds (About 6.7Mbps which is about the max my line can handle given ATM overheads). When I moved to openvpn ethernet bridging mode, I am getting capped at exactly 6Mbps:

Here is a graph of 50% of a Samba transfer of a 400MB file (I stoped it half way through):

http://www.tripathy.org/openvpn-transfer.jpg

Does anyone know why bridging would cause this? Being capped at 6Mbps exactly is strange. Do you think there is some limatation that the vmware NIC or possible the remote machine (which is also a virtual machine) can handle?

I know it's only around 1Mbps difference but it's driving me crazy not knowing why!

Thanks