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

  • Subject: [Openvpn-users] Re: VPN & ADSL Adapter Speed Comparison
  • From: Steve Shellswell <steve@xxxxxxxxxxxxxxxx>
  • Date: Thu, 23 Dec 2004 12:06:36 +0000

Leonard Isham wrote:
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

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?

mmm, nothing on the client end, server end not certain but I hadn't imagined much.

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

I am reasonably confident to say that we get near the purchased maximum.

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.

Sage Accounting. When you load the Nominal window, the first time while it gathers data from the server takes about 3.5 mins, during which time I observed the numbers above.

Really my surprise was down to the VPN adapter putting through 256 and the real one 80. This is quite an impressive compression ratio. You might be right that servers other bandwidth was being used and so limited the ADSL to 80, and that it is then just coincidence that the VPN adapter was going at 256...


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