WiscNet runs an IPERF version 2 server in Eau Claire, WI. The server is restricted to WiscNet IP addresses.
Examples
iperf.wiscnet.net runs a TCP Iperf server on the default port (5001)
iperf -c iperf.wiscnet.net -i2
iperf.wiscnet.net runs a UDP Iperf server on port 5002. this test uses UDP, sends 20Mb/s, reports every 2 seconds, runs for 30 seconds
iperf -c iperf.wiscnet.net -u -b20M -p 5002 -i2 -t30
iperf.ipv6.wiscnet.net runs a v6 TCP Iperf server on port 5003
iperf -V -c iperf.ipv6.wiscnet.net -p 5003 -i2
iperf.ipv6.wiscnet.net runs a v6 UDP Iperf server on port 5004
iperf -V -c iperf.ipv6.wiscnet.net -p 5004 -i2 -u
TCP vs UDP testing
Iperf uses TCP by default. TCP has built in congestion avoidance. If TCP detects any packet loss, it assumes that the link capacity has been reached, and it slows down. This works very well, unless there is packet loss caused by something other than congestion. If there is packet loss due to errors, TCP will back off even if there is plenty of capacity. iperf allows TCP to send as fast as it can, which generally works to fill a clean, low latency link with packets. If a path is not clean/error free or has high latency, TCP will have a difficult time filling it. For testing higher capacity links and for links with higher latency, you will want to adjust the window size (-w option). See the KB article on TCP performance for more background.
By using the -u option, you have told iperf to use UDP packets, rather than TCP. UDP has no built in congestion avoidance, and iperf doesn't implement it either. When doing a UDP test, iperf requires that the bandwidth of the test be specified. If it isn't, it defaults to 1Mb/s. You can use the -b option to specify bandwidth to test. iperf will then send packets at the request rate for the requested period of time. The other end measures how many packets are received vs how many were sent and reports its results.
Bidirectional tests
When you use the '-d' or '-r' options for bidirectional testing, I find that you need to pick a port other than the default [5001] as the server is listening on port 5001. In the below examples, I picked random ports above 1024.
I found that using the same port (with the -L) option in rapid succession doesn't seem to work. I don't know what the deal is with that, I assume it is a server end FW issue that times out.
The simultaneous test results are a little difficult to read. It looks like only TCP is working. UDP doesn't appear to be working even after upgrading to iperf-2.0.4 [there were supposed to be some bug fixes]. It appears to be a problem in the official distribution according to recent ubuntu forums.
! not picking port doesn't work
C:\>iperf -c iperf.wiscnet.net -i1 -d
bind failed: Permission denied
! simultaneous, local port 20000
C:\>iperf -c iperf.wiscnet.net -i1 -d -L 20000
------------------------------------------------------------
Server listening on TCP port 20000
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to iperf.wiscnet.net, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1848] local 146.151.208.16 port 2242 connected with iperf.wiscnet.net port 5001
[1820] local 146.151.208.16 port 20000 connected with iperf.wiscnet.net port 20000
[ ID] Interval Transfer Bandwidth
[1848] 0.0- 1.0 sec 1.03 MBytes 8.65 Mbits/sec
[1820] 0.0- 1.0 sec 1.05 MBytes 8.83 Mbits/sec
[1848] 1.0- 2.0 sec 1.09 MBytes 9.11 Mbits/sec
[1820] 1.0- 2.0 sec 911 KBytes 7.46 Mbits/sec
[1848] 2.0- 3.0 sec 976 KBytes 8.00 Mbits/sec
[1820] 2.0- 3.0 sec 1.05 MBytes 8.79 Mbits/sec
[1820] 3.0- 4.0 sec 1.33 MBytes 11.1 Mbits/sec
[1848] 3.0- 4.0 sec 672 KBytes 5.51 Mbits/sec
[1848] 4.0- 5.0 sec 712 KBytes 5.83 Mbits/sec
[1820] 4.0- 5.0 sec 1.38 MBytes 11.5 Mbits/sec
[1848] 5.0- 6.0 sec 624 KBytes 5.11 Mbits/sec
[1820] 5.0- 6.0 sec 1.42 MBytes 11.9 Mbits/sec
[1848] 6.0- 7.0 sec 584 KBytes 4.78 Mbits/sec
[1820] 6.0- 7.0 sec 1.53 MBytes 12.9 Mbits/sec
[1848] 7.0- 8.0 sec 832 KBytes 6.82 Mbits/sec
[1820] 7.0- 8.0 sec 1.26 MBytes 10.5 Mbits/sec
[1848] 8.0- 9.0 sec 616 KBytes 5.05 Mbits/sec
[1820] 8.0- 9.0 sec 1.49 MBytes 12.5 Mbits/sec
[1848] 9.0-10.0 sec 584 KBytes 4.78 Mbits/sec
[1820] 9.0-10.0 sec 1.51 MBytes 12.7 Mbits/sec
[ ID] Interval Transfer Bandwidth
[1848] 0.0-10.0 sec 7.59 MBytes 6.34 Mbits/sec
[1820] 0.0-10.1 sec 13.1 MBytes 10.9 Mbits/sec
! Here is a back to back test; the server to client test comes AFTER the client to server test.
C:\Documents and Settings\m7h>iperf -c iperf.wiscnet.net -i1 -r -L 60000
------------------------------------------------------------
Server listening on TCP port 60000
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
------------------------------------------------------------
Client connecting to iperf.wiscnet.net, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[1848] local 146.151.208.16 port 2365 connected with iperf.wiscnet.net port 5001
[ ID] Interval Transfer Bandwidth
[1848] 0.0- 1.0 sec 2.02 MBytes 17.0 Mbits/sec
[1848] 1.0- 2.0 sec 1.91 MBytes 16.1 Mbits/sec
[1848] 2.0- 3.0 sec 1.92 MBytes 16.1 Mbits/sec
[1848] 3.0- 4.0 sec 1.92 MBytes 16.1 Mbits/sec
[1848] 4.0- 5.0 sec 1.92 MBytes 16.1 Mbits/sec
[1848] 5.0- 6.0 sec 1.95 MBytes 16.3 Mbits/sec
[1848] 6.0- 7.0 sec 1.98 MBytes 16.6 Mbits/sec
[1848] 7.0- 8.0 sec 1.95 MBytes 16.4 Mbits/sec
[1848] 8.0- 9.0 sec 1.89 MBytes 15.9 Mbits/sec
[1848] 9.0-10.0 sec 2.04 MBytes 17.1 Mbits/sec
[1848] 0.0-10.0 sec 19.5 MBytes 16.4 Mbits/sec
[1824] local 146.151.208.16 port 60000 connected with iperf.wiscnet.net port 60000
[ ID] Interval Transfer Bandwidth
[1824] 0.0- 1.0 sec 2.22 MBytes 18.6 Mbits/sec
[1824] 1.0- 2.0 sec 2.18 MBytes 18.3 Mbits/sec
[1824] 2.0- 3.0 sec 2.17 MBytes 18.2 Mbits/sec
[1824] 3.0- 4.0 sec 2.22 MBytes 18.6 Mbits/sec
[1824] 4.0- 5.0 sec 2.01 MBytes 16.9 Mbits/sec
[1824] 5.0- 6.0 sec 2.16 MBytes 18.1 Mbits/sec
[1824] 6.0- 7.0 sec 2.09 MBytes 17.5 Mbits/sec
[1824] 7.0- 8.0 sec 2.07 MBytes 17.4 Mbits/sec
[1824] 8.0- 9.0 sec 2.16 MBytes 18.1 Mbits/sec
[1824] 9.0-10.0 sec 2.13 MBytes 17.9 Mbits/sec
[1824] 0.0-10.1 sec 21.6 MBytes 17.9 Mbits/sec