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[Openvpn-users] Subject:, speed

  • Subject: [Openvpn-users] Subject:, speed
  • From: Peter Barwich <pbarwich@xxxxxxxxxxx>
  • Date: Sun, 26 Aug 2007 15:56:16 +0100


I have to say I cannot repeat your results. I have two IP's at home so can experiment. Even better as far as I can tell they connect via the ISP router, not over the wider internet, so ping times are very low (2-3 msec).. I have a Win2k machine set up as an OVPN server, and an XP laptop set up as an OVPN client. . Whichever way I route ftp (via OVPN or IP address) I get around the same speed (around 220kB which is around my ISP limit, up and down). I have confirmed the packets are actually going via VPN or not by looking at the Microsoft management consol for networks at each adaptor.

I use UDP also and WOULD NOT use TCP. Google 'TCP over TCP is a bad idea'. However I also use dev TAP (not TUN as you do). This means that remote machines do not come up in network neighbourhood as NETBIOS doesn't work, (and in any case I've turned off netbios over TCP for the OVPN adaptor), but I map remote disk drivers via the address (or via the machine name since I have my own DNS server). I have read that standard windows file sharing kills speed, mainly due to a large number of small packets, so I just wondered if by using TUN you are unknowingly invoking windows file sharing? Not sure about that, I admit, but worth your while remeasuring with dev TAP connections I would have thought.

Good luck,

[Openvpn-users] speed
"Mira Suk" <mira.suk@xxxxxxxxxx>
Sat, 25 Aug 2007 21:29:06 +0200


openVPN 2.0.9
server Windows SBS 2003
clients Window XP / Vista

TUN, UDP , blowfish / compression on

Are following speeds normal (in that configuration) or should I look for something wrong ? Any recommendations ? (note I tried disabling compression but nothing changed - file was compressed and OpenVPN is smart ;)

file download (one big file :)
File sharing through VPN         62 minutes
FTP through VPN                       53 minutes
FTP without VPN                        32 minutes
pings are great I would say.
ping through VPN                      ~23 ms 
ping without VPN                       ~19 ms

I have never troubleshooted slowness with OpenVPN, but this link is slow (2MBit)... and I have not used win2K3 before (only linux and win2K)

Oh, and I noticed option "nice" is not implemented for windows [SetPriorityClass, SetThreadPriority] can be used (If I haven't been too lazy to dig in source, I wouldn't have hardcoded it), also CPU affinity makes some small benefits under windows.

Thanks for any hints.