ohmer
join:2003-08-06
Quebec, QC
 ·TekSavvy Solutions..
 ·Primus Talkbroadband
·Mega Qubec
| OpenVPN overhead
Hello,
I use OpenVPN to bypass the Hell throttling. Since I use that, I see that I transfer a lot more data than before.
If I look at the data transfer rate that pass to eth0 (my real network interface) and tun0 (my vpn interface), I see a difference of ~10kb/s right now upstream (eth0 is uploading at 60kb/s, tun0 is uploading at 50kb/s). It's an overhead of 843 mb by day for 4.2gb of real traffic if I upload 24/24 !
There is something I'm missing on my OpenVPN configuration to reduce the overhead ?
My config is
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TI-Québec : Forum des professionnels en TI au Québec. |
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anonman
@teksavvy.com | I'm quite sure openvpn supports compression (lzo I think). I don't see one of the options mentioning it at all. |
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Orange Box
@teksavvy.com | reply to ohmer
Ohmer, I am happy that you've managed to bypass the throttling with VPN. The sad part is that eventually Bell will start throttle VPN as well and that day I would not be very happy since I rely on it to administer remote servers. |
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Taylortbb
Premium
join:2007-02-18
Waterloo, ON
·TekSavvy Solutions..
| said by Orange Box :
Ohmer, I am happy that you've managed to bypass the throttling with VPN. The sad part is that eventually Bell will start throttle VPN as well and that day I would not be very happy since I rely on it to administer remote servers.
I doubt Bell would try and throttle VPN. Right now they can pass it off as bandwidth hogs, but as soon as it starts interfering with people working from home that excuse will be exposed as BS. Lawyers are ferocious, and they need VPN to work from home. 
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Taylor Byrnes
www.taylorbyrnes.org |
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ohmer
join:2003-08-06
Quebec, QC
·TekSavvy Solutions..
·Primus Talkbroadband
·Mega Qubec
| said by Taylortbb  :I doubt Bell would try and throttle VPN. Right now they can pass it off as bandwidth hogs, but as soon as it starts interfering with people working from home that excuse will be exposed as BS. Lawyers are ferocious, and they need VPN to work from home. Yeah, they cannot do anything against vpn traffic.
Will try the lzo compression if this change something.
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TI-Québec : Forum des professionnels en TI au Québec. |
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ohmer
join:2003-08-06
Quebec, QC
·TekSavvy Solutions..
·Primus Talkbroadband
·Mega Qubec
| reply to anonman
said by anonman :
I'm quite sure openvpn supports compression (lzo I think). I don't see one of the options mentioning it at all.
No changes with lzo compression.
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TI-Québec : Forum des professionnels en TI au Québec. |
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Name96
join:2008-03-28
| reply to ohmer
Configuring OpenVPN is a bit of a black art.
The best you can do to minimize overhead is enable LZO and maximize the fragment and mssfix directives to the limits of your connection.
To find the largest fragment size you can use, determine the largest DF packet you can send with ping -f -l xxxx and add 65 bytes to that value. Use this for OpenVPN's fragment and mssfix directives.
If you're feeling adventurous and really want an extra four bytes of payload per packet, remove the fragment directive and increase mssfix by four bytes. Be advised this will break any UDP-based applications which expect/depend on a 1500 byte MTU.
I believe PPTP has slightly lower per-packet overhead than OpenVPN. It might be worth trying PPTP if PPTP's security flaws aren't an issue for your needs.
N.B. Bell molests at least some forms of IPSEC.
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Coridon Henshaw -=- »www.talisiorder.ca |
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CanerisErik
Caneris
Premium,VIP
join:2007-10-03
Toronto, ON
1 edit | reply to ohmer
If there was a widespread issue with OpenVPN, I'd be the first yelling, and very loudly!
So it hasn't hit yet, or haven't noticed, or they're not throttling it. |
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An Onymous
@teksavvy.com
|  reply to ohmer
Found this webpage on google (3rd result!) on the overhead involved:
I have converted it to a jpeg attachment to preserve the formatting.
»mia.ece.uic.edu/~papers/volans/o···ults.htm
The full wepage for setting up OpenVPN is here:
»mia.ece.uic.edu/~papers/volans/openvpn1.html |
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