OpenVPN Support Forum

Posted: **Fri Jan 14, 2011 4:30 pm**

Hello.
I have a question, probably more theoretical (but caused a real problem) ...
The main office has a connection to SDSL (1Mb Up/Down) and behind the server OpenVPN 2.0.
Always connected to the server 3 clients (other offices), and sometimes connect roadwarriors.
server.conf:

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dev tun
udp
comp-lzo

Clients are experiencing great difficulties when working through a tunnel. Everything works, but the rate of such transfer files via FTP, or SMB/CIFS is very low!

I would like to ask how OpenVPN divides the channel between the 3 - 4 clients? Each connection is allocated a fixed bandwidth or dynamic bandwidth?

Using iperf, I measured the speed in the tunnel from each client:
Client 1

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# iperf -c 192.168.1.12 -i2
------------------------------------------------------------
Client connecting to 192.168.1.12, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  3] local 192.168.13.102 port 50200 connected with 192.168.1.12 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0- 2.0 sec    216 KBytes    885 Kbits/sec
[  3]  2.0- 4.0 sec  96.0 KBytes    393 Kbits/sec
[  3]  4.0- 6.0 sec    144 KBytes    590 Kbits/sec
[  3]  6.0- 8.0 sec    144 KBytes    590 Kbits/sec
[  3]  8.0-10.0 sec  88.0 KBytes    360 Kbits/sec
[  3]  0.0-10.1 sec    696 KBytes    563 Kbits/sec

Cliente 2

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iperf -c 192.168.1.12 -i2
------------------------------------------------------------
Client connecting to 192.168.1.12, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1884] local 192.168.3.206 port 3978 connected with 192.168.1.12 port 5001
[ ID] Interval       Transfer     Bandwidth
[1884]  0.0- 2.0 sec  72.0 KBytes   295 Kbits/sec
[1884]  2.0- 4.0 sec  8.00 KBytes  32.8 Kbits/sec
[1884]  4.0- 6.0 sec  48.0 KBytes   197 Kbits/sec
[1884]  6.0- 8.0 sec  48.0 KBytes   197 Kbits/sec
[1884]  8.0-10.0 sec  40.0 KBytes   164 Kbits/sec

Client3

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iperf -c 192.168.1.12 -i2
------------------------------------------------------------
Client connecting to 192.168.1.12, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[888] local 192.168.20.22 port 2583 connected with 192.168.1.12 port 5001
[ ID] Interval       Transfer     Bandwidth
[888]  0.0- 2.0 sec   208 KBytes   852 Kbits/sec
[888]  2.0- 4.0 sec   240 KBytes   983 Kbits/sec
[888]  4.0- 6.0 sec   168 KBytes   688 Kbits/sec
[888]  6.0- 8.0 sec   208 KBytes   852 Kbits/sec
[888]  8.0-10.0 sec   240 KBytes   983 Kbits/sec

And I always have problems with the second client (the biggest office)

Posted: **Thu Jan 20, 2011 9:00 pm**

serjsk8 wrote: The main office has a connection to SDSL (1Mb Up/Down) and behind the server OpenVPN 2.0.

The server only has 1mbit, that is a slow connection... also remember that any communications between clients will always flow through the server, so for 2 other offices to xfer between eachother will require everything to go over the server.

I would like to ask how OpenVPN divides the channel between the 3 - 4 clients? Each connection is allocated a fixed bandwidth or dynamic bandwidth?

This is not openvpn's job. Your kernel will handle this. You may apply QOS rules to it in your normal firewall if you like.

Posted: **Sat Jan 22, 2011 1:14 am**

So basicly you have established openvpn is running @ home office ok, and is capable to match the speed at leat four times. Except for office #2. I'd start looking there. crappy server ? low uplink. xdsl busy doing other stuff ? etc

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