Thursday, February 16, 2012

Measuring network throughput with iperf

The iperf tool has been around for ages and yeah, I've been late to the game :)

To install iperf in Ubuntu, it's a simple apt-get away:
$ sudo apt-get install iperf
To run the test, you'll need 2 machines.  One to act as the server and the other as the client.  Start by starting the server:
$ iperf -s
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
If there are no errors, we can then start the test by executing iperf in the client machine:
$ iperf -c server -t 10
Client connecting to server, TCP port 5001
TCP window size: 16.0 KByte (default)
[  3] local port 40913 connected with port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec    164 MBytes    138 Mbits/sec
The argument -t 10 states that we want the test to run for only 10 seconds. 

There are other options which you can play with like:

    -d ==> Do a bidirectional test simultaneously
    -u ==> use UDP rather than TCP
View the list of options by executing:
$ iperf --help
There's also a GUI wrapper written in Java for iperf available at  It offers a nice GUI which allows you to choose different options to run iperf with and also displays output from iperf in a nice graph:

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