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Re: [Openvpn-users] VPN & ADSL Adapter Speed Comparison

  • Subject: Re: [Openvpn-users] VPN & ADSL Adapter Speed Comparison
  • From: Leonard Isham <leonard.isham@xxxxxxxxx>
  • Date: Wed, 22 Dec 2004 13:54:37 -0500

On Wed, 22 Dec 2004 17:22:28 +0000, Steve Shellswell
<steve@xxxxxxxxxxxxxxxx> wrote:
> Dear all,
> I have two machines both connected via ADSL (512 down and 256 up) to the
> Internet. On side is running an openvpn server (debian) and the other is
> a client (Windows XP).
> Whilst on the client XP end pulling a few MB across the VPN, I was
> looking at the Network Utilization tool that Win XP has (ctrl,shift &
> esc) and was comparing the usage of the VPN adapter to the ADSL modem
> adapter.
> The VPN adapter was sat right on about 2.5% usage and Windows thinks it
> is 10Mbps. The ADSL adapter was pretty consistently on 13-15% and
> windows thinks its maximum is 576kbps.
> 2.5% of 10Mbps is 256kbps and this looked good because the uplink on the
> server end is 256, but 14% of 576kbps is about 80kbps.
> It therefore seemed to me that the VPN adapter was putting stuff through
> at 256kbps. VPN was compressing it and transmitting down the real ADSL
> adapter at around 80kbps. Am I right?
> Why then, for example, did VPN not use 90-100% of the available ADSL
> line and get a throughput over the VPN adapter of three times 256? Is
> there anyway to tell VPN to use all of the available link? Is it, do you
> think, that XP cant count the usage properly?
> Many thanks for your thoughts....

First since both sides are limited to 256 up your limitation is 256

Second what else is using the lines when you test?

Third are you actually reaching your purchased maximum or not?  Have
you tried using dslreports to test?

Fourth What application(s) are in use what is their traffic patterns. 
With FTP you get higher bandwidth on one direction with the other
direction getting minimal usage.

Leonard Isham, CISSP 
Ostendo non ostento.

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