[thelist] Windows VPN Analysis

Kelly Hallman khallman at wrack.org
Tue Sep 16 01:51:17 CDT 2003

On Mon, 15 Sep 2003, Hershel Robinson wrote:
> My aDSL connection works just fine for regular HTTP communications with
> the server, but VPN communications proceed VERY slowly.

So when you access an http server on the same network, it gets a good
rate, but when you enable VPN, the connection degrades considerably? I am
assuming you are testing equally large files and that they are actually on
the same network (as even two networks in the same locale may have
radically different reliability).

VPN traffic is usually heavier than normal IP protocol traffic due to the
fact that it's encrypted (which is what makes the data larger).

That would make it slower, but if the difference is extreme, then the
problem may be on the other end. Like anything involving a lot of number
crunching (encryption/decryption), a VPN server has pretty massive
performance requirements. It could be over-burdened.

> I have NetMedic so I can see the speed of the communications, but I am now
> looking for something more detailed and lower level to analyze what is
> happening and hopefully determine a solution to allow us to proceed faster.

I'm guessing if the only variable is the VPN (off you get good rates, on 
makes everything slow AND both destinations are on the same network) then 
trying to analyze the connection from your end is probably not going to 
tell you too much. You may be able to actually verify that the connection 
gets slower, which would also point to a capacity probably on the 
remote VPN server, but you won't have much recourse locally.

> I connect to the VPN (over the great ocean, heh heh) to a Netopia 4522
> router at headquarters.

Is the router actually doing the VPN or is that going to a server on that
network? If it's a server doing software encryption/decryption and there
are more than a few VPN users, I'd be suspicious of that machine.

Kelly Hallman

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