OpenVPN TAP Speeds

Comments

• SplitIce Member, Host Rep

  December 2014

  TAP itself is perfectly fine for performance. My software to bring IP-in-IP & GRE to windows easily maxes a my AC wireless (~300-400mbps). Chews about 30% of my laptops CPU to do that, but that's to be expected with the copying (In my case its kernel -> user space -> kernel).

  More than likely its to do with the configuration or overheads in OpenVPN. Look for misconfiguration like TCP over TCP or MTU/MSS issues.
• PrincessOfCats Member

  December 2014 edited December 2014

  Ive been tinkering with it a bit, and I have managed to get it to around 15Mbits/s, though I do feel that is still kind of low. Here is my openvpn client config http://pastebin.com/LBegSAkB and my openvpn server config http://pastebin.com/Cg574mnh

  Currently, the tests are done using iperf -s/-c

  These are all on gigabit VPSes, so I seriously do not know what the problem is.

  Edit #2:
  Yanking out the bridge, and making dnsmasq listen directly on the tap interfaces seems to have increased the speed a bit to 20Mbits/s

  Edit #3:
  Ah ha!
  The solution was to set the mtu of the tap interface to 48000 on both server and client. That returns the speed to around 181-300 MBits/sec which is much more reasonable
• ValdikSS Member

  December 2014 edited December 2014

  StartledPhoenix said: Edit #3: Ah ha! The solution was to set the mtu of the tap interface to 48000 on both server and client. That returns the speed to around 181-300 MBits/sec which is much more reasonable

  Better not to do that

  Try this:

  txqueuelen 300
  sndbuf 393216
  rcvbuf 393216
  push "sndbuf 393216"
  push "rcvbuf 393216"
  

  If it helps, please vote here https://community.openvpn.net/openvpn/ticket/461

  Also, mssfix consumes a lot of CPU. Turn it off with

  mssfix 0
  

  on both sides and use iptables TCPMSS if you need it.