flyingrhino
Hi,
I'm experiencing strange openvpn 2.4 behavior -
I get really bad transfer speeds when the other direction of the link is not in use.
For example - if I am transferring a file by scp, there is a lot of traffic in one direction, but very little in the other (mostly small ack packets). This causes the transfer to go really slow - mostly for windows clients.
What I found is that if I generated some traffic in the "low traffic direction" , the transfer reached my full line speed!
I can't explain why this occurs, other than a speculation that openvpn is buffering the "slow speed" direction, which results in the "high speed" direction getting slowed down.
For example - I can achieve 30Mbps upload on my link. But if I do ONLY UPLOAD, I might get only 1-4Mbps upload speed (it varies all the time).
Now, if I download something at the same time (even slowly at 2Mbps), the upload will max the link at 30Mbps.
The v2.4 openvpn server runs on linux.
The clients that cause problems are mostly windows. I've very rarely experienced this slow speed behavior on linux.
I have a mix of windows and linux clients, so pushing settings need to be compatible with both client platforms.
Do you have any suggestions how I can resolve it ? Preferably at the server side, because this is the only end I fully control.
Thanks.
server.conf:
I've removed "private" information lines like sever address, keys, etc
topology subnet
proto udp
dev tun
mssfix 1300
sndbuf 393216
rcvbuf 393216
push "sndbuf 393216"
push "rcvbuf 393216"
tcp-nodelay # I don't think I need this due to 'proto udp' above...
tcp-queue-limit 128 # I don't think I need this due to 'proto udp' above...
txqueuelen 2000
script-security 2
keepalive 2 20
reneg-sec 1800
persist-key
persist-tun
verb 4
mute 3
explicit-exit-notify 1
