Low Bandwidth with openvpn

vishal1kumar

Hi community members,
This have been asked earlier in the the group but want to understand is this expected.

I am using openvpn cli client (ovpncli latest) and WinTUN driver. [https://github.com/OpenVPN/openvpn3]
I have my test all testup created on a single Esxi server and sufficient resources (CPU and memory) is given to the machines.

Without any tunneling the bandwidth I am getting is 10-12 gbps, but when I introduce the openvpn tunnel the bandwidth drops to 300-350 mbps.

What is it the maximum bandwidth openVPN tunnel can support? Is it 300-350mbps only?

Thanks

vishal1kumar

My Client ovpn config file looks like:
client
dev tun
#tun-mtu 9000
windows-driver wintun
proto udp
remote 10.213.175.203 443
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
auth SHA512
cipher AES-256-CBC
ignore-unknown-option block-outside-dns
block-outside-dns
redirect-gateway def1
route-nopull
verb 3
<ca>

============================
I am using WinTUN driver.

============================
Bandwidth without OpenVPN:
.\iperf3.exe -c 10.213.175.203
Connecting to host 10.213.175.203, port 5201
[ 4] local 10.213.175.205 port 64352 connected to 10.213.175.203 port 5201
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-1.02 sec 450 MBytes 3.70 Gbits/sec
[ 4] 1.02-2.00 sec 424 MBytes 3.63 Gbits/sec
[ 4] 2.00-3.00 sec 203 MBytes 1.70 Gbits/sec
[ 4] 3.00-4.00 sec 169 MBytes 1.42 Gbits/sec
[ 4] 4.00-5.02 sec 263 MBytes 2.17 Gbits/sec
[ 4] 5.02-6.05 sec 346 MBytes 2.81 Gbits/sec
[ 4] 6.05-7.00 sec 302 MBytes 2.66 Gbits/sec
[ 4] 7.00-8.00 sec 195 MBytes 1.64 Gbits/sec
[ 4] 8.00-9.02 sec 171 MBytes 1.42 Gbits/sec
[ 4] 9.02-10.00 sec 393 MBytes 3.34 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 2.85 GBytes 2.45 Gbits/sec sender
[ 4] 0.00-10.00 sec 2.85 GBytes 2.45 Gbits/sec receiver

============================
Bandwidth with OpenVPN (WinTUN):

.\iperf3.exe -c 10.213.175.203
Connecting to host 10.213.175.203, port 5201
[ 4] local 10.8.0.2 port 54008 connected to 10.213.175.203 port 5201
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-1.00 sec 34.5 MBytes 289 Mbits/sec
[ 4] 1.00-2.00 sec 43.0 MBytes 362 Mbits/sec
[ 4] 2.00-3.00 sec 32.5 MBytes 272 Mbits/sec
[ 4] 3.00-4.00 sec 43.4 MBytes 365 Mbits/sec
[ 4] 4.00-5.00 sec 43.0 MBytes 361 Mbits/sec
[ 4] 5.00-6.00 sec 39.4 MBytes 330 Mbits/sec
[ 4] 6.00-7.00 sec 44.5 MBytes 374 Mbits/sec
[ 4] 7.00-8.01 sec 40.5 MBytes 337 Mbits/sec
[ 4] 8.01-9.00 sec 30.9 MBytes 260 Mbits/sec
[ 4] 9.00-10.00 sec 39.4 MBytes 331 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 391 MBytes 328 Mbits/sec sender
[ 4] 0.00-10.00 sec 391 MBytes 328 Mbits/sec receiver

iperf Done.

====================================
I also verified there is no fragmentation issue, PMTU for both with and without VPN is 1472
What am i doing wrong?