vpn speed loss

[Zane C. B-H.]

On Fri, 1 Jun 2012 11:48:45 +0200
Beni Brinckman <beni.brinckman at gmail.com> wrote:

> Hi,
> 
> I'm running FreeBSD 9.0-RELEASE (pc-bsd 9.0 actuallly) on amd64 and
> I'm using a vpn connexion.
> My problem is the enormous speed loss i'm having when I'm using the
> vpn connexion.
> I have tried Openvpn and mpd5 (with a pptp and l2pt connexion) and
> the max speed (according to various speedtests) is 5 to 6MB.
> Without the vpn I'm having 45-50 MB... My vpn service has servers in
> several European countries and US, Canada, etc. The speed stays the
> same.
> So I don't  think it is a specific bsd problem but the
> lines/connexion between ISP's.
> Is this the "normal" speed when using a vpn (independently of the
> used program to connect) ? Because from 45-50 back to 5-6 is a big
> step backward...
> Thanks for any insights here.

With OpenVPN, you should not be seeing that big of a drop, with the
real limiting factor being the CPU time available for it. You can
easily check top and see if that is the case.

If you get 45-50MBps between the two locations with out VPN, baring
any firewall issues at either end, it is likely a configuration issue
in regards to the networking of the machines in question or the VPN
software or a CPU resource issue.

One of the first areas I would check is the MTU being used on the
network interfaces, figure out what the max MTU for the path is, and
make sure the VPN software is not sending packets larger than that.

You may also want to take a look at tuning(7).