Hi, I'm having some issues when attempting to run iperf over an OpenVPN TCP tunnel. My setup consists of 2 Openstack Linux VMs with Gigabit Ethernet between them. When measuring the bandwidth between the VMs without any tunnel, I get aroung 950Mbps.
However, when I use a TCP tunnel, things are weird. The tests that finish report a bandwidth of around 500Kbps (yes, Kbps, that is no typo). Most of the time however, the tests just hang. If i try to stop the server-side iperf, I get the following message: "Waiting for server threads to complete. Interrupt again to force quit.". After interrupting the iperf, the OpenVPN tunnel is unusable, as in I cannot even ping the other peer. I have used various options to reduce the overhead introduced by OpenVPN, based on the tips from a community article[1]. Currently I am starting the OpenVPN tunnel like this: openvpn --daemon --remote $CLIENT_IP --proto tcp-server --dev tun1 --ifconfig $SERVER_TUNNEL_IP $CLIENT_TUNNEL_IP --cipher none --auth none --fragment 0 --mssfix 0 --tun-mtu 10000 and a similar command on the client, but with the IPs changed and the tcp-client protocol. I understand that TCP over TCP should behave badly since the congestion algorithm from the nested TCP will interfere with the congestion algorithm from the outer TCP, but something doesn't seem right. I've tried debug logs, strace logs, ltrace logs, looking in dmesg, but I couldn't find any error messages that would provide an answer. Should the bandwidth drop so dramatically, from 950Mbps to 500Kbps? Should iperf hang like this? Why is the OpenVPN tunnel unusable afterwords? Has anyone experienced something similar before? [1] https://community.openvpn.net/openvpn/wiki/Gigabit_Networks_Linux Thank you, Silviu Popescu ------------------------------------------------------------------------------ Time is money. Stop wasting it! Get your web API in 5 minutes. www.restlet.com/download http://p.sf.net/sfu/restlet _______________________________________________ Openvpn-users mailing list Openvpn-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/openvpn-users
