User profile for user: Fluffy Gimp
Fluffy Gimp Author
User level: Level 1
8 points

Network Speed with VPN

Hello,

I've got a strange internet speed issue when I'm connected to a VPN. When the VPN is disconnected my internet speed is lightning-fast but as soon as I connect my VPN it slows to a crawl. The "use VPN for all traffic" tick box in the VPN settings is not ticked. I ran trace routes with the VPN on and off and the traffic goes the same route from my office to google.com but the only difference is that with the VPN off the trace takes 4 seconds but with it on it takes several minutes to run! I noticed that switching on the VPN messed up my default route to the internet so I made a shell script to put correct route back in the routing table once the VPN is connected.

Can anybody help?

Thanks,

Stu

MacBook, Mac OS X (10.5.6)

Posted on Apr 7, 2009 8:06 AM

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7 replies
User profile for user: Dewser
Dewser
User level: Level 1
8 points

Apr 8, 2009 7:48 AM in response to Fluffy Gimp

Is your local network configured similarly to your remote network? For example are you using a popular local private IP range 192.168.0.x? If so is your remote network doing a similar IP scope? The answer to the speed issue is that your system is configured to use a gateway of 192.168.0.1 and if you are getting a VPN IP of a similar address, your system is sending traffic destined for your local gateway through the VPN. Basically its confused.

Usually I recommend that users configure their home networks to be a different IP range from their work networks, especially if they do a lot of work from home or remote office.
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User profile for user: keggo
keggo
User level: Level 1
45 points

Apr 7, 2009 4:56 PM in response to Fluffy Gimp

VPN is a very secure way to connect to a remote site. The only way this happens is because the connection is completely encrypted and a "tunnel" is created to separate the VPN connection from all other internet traffic. This is why your VPN connection is ******** slow. There is a lot of calculations that need to be made by both ends of the connection to read the real payload inside the packets. That is the encryption and decryption that is taking place, and that is what you notice to be a slow connection. Even though you do not have the tick box checked it is not a for sure setting that the data being sent will not be sent over the VPN tunnel, is more like it makes sure that data destined for the VPN tunnel travels that route not the other way around.
As for setting a static route, personally I think that is a bad idea, because the ISPs have more knowledge of routes than we do and they may feel that your route to the office is not the best route. But if it works then I really cant say not to do it, no!
hope that helps.
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User profile for user: Fluffy Gimp
Fluffy Gimp Author
User level: Level 1
8 points

Apr 8, 2009 1:30 AM in response to keggo

Hi,

Thanks for your help but my problem may have been misunderstood. My VPN connection isn't slow - it's all the other non-VPN internet traffic (web browsing) that is slow, but only when the VPN is connected. I know the internet traffic is using the same route whether the VPN is connected or not so I can't understand why internet traffic should be slower when the VPN is on.
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Network Speed with VPN

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