How to increase the VPN BANDWIDTH ?

Unanswered Question
Feb 21st, 2011
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Hello,


Is it possible to increase the bandwidth of a VPN connection ?


When I connect my home network without VPN , is is very fast , when I switch on VPN the speed decrease dramatically , even if I have now a AIM / VPN module in my CISCO 1841 ROUTER.


Any idea if it is possible ?


At my provider (where my CISCO 1841 router is) I have a DOWNLOAD of 60MB and UPLOAD f 3MB.


When I just ping from abroad with VPN it is 50mSec , without VPN it is 15mSec.


Thank you in advance for your help


Best Regards,

Didier

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Didier1966 Thu, 02/24/2011 - 14:11
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Is this question stupid or to complicated ?


I just did a test with a CISCO 610N with a DD-WRT firmware on it with VPN , and it is faster than my CISCO 1841 !!!

A LINKSYS WRT54GL is at the same speed than my CISCO 1841 !!!


This can not be true



Any help or idea is welcome.



Best Regards,

Didier

Federico Coto F... Thu, 02/24/2011 - 15:32
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Didier,


Sometimes what happen is that there's fragmentation occuring when using VPN (since IPsec adds overhead to the IP packets).

You can decrease the TCP MSS on the inside interface to try to avoid fragmentation.


If fragmentation is going to happen, then it should have before encryption (not after).


Also, if you have other configuration that might be affecting the VPN traffic?


You can do a quick test... can you test if ICMP traffic is affected or only TCP?

Attempt a PING and check the response time when/without VPN.


If the PINGs are fine, and the problem is only with TCP, we might adjust some TCP settings.


Federico.

Didier1966 Tue, 03/01/2011 - 14:11
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Hello Federico,


Sorry for my late reply.


Do you have some example or tools how to do this ?


Thank you in advance for your help


Best Regards,

Didier.

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