TechniTip.Net

Network Bandwidth Performance Measurement with Iperf

Another easy to use tool for measuring the network bandwidth is Iperf. On Debian it can be installed using:

apt-get install iperf

Optionally the source or the Windows binary is available from sourceforge.net/projects/iperf

Building and installing from source is done using a few commands:

tar xvfz iperf-2.0.4.tar.gz
cd iperf-2.0.4
./configure
make
make install

Once installed iperf the server is started on machine 1:

machine1:~# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------

Next the client is started on machine 2:

machine2:~# iperf -c machine1.mydomain.de
------------------------------------------------------------
Client connecting to machine1.mydomain.de, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[  3] local xx.xx.xx.xx port 45325 connected with yy.yy.yy.yyport 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  96.6 MBytes  80.9 Mbits/sec

Tested on two servers connected with 100 MBit/s located at two different providers in Germany we get a result of 80.9 MBits/sec.

This result is slightly higher compared to the result from our measurement done with NETIO in the article Network Throughput Measurement. So we start the test again with addtional parameters:

machine2:~# iperf -c machine1.mydomain.de -w 512k -l 512k
------------------------------------------------------------
Client connecting to machine1.mydomain.de, TCP port 5001
TCP window size:   256 KByte (WARNING: requested   512 KByte)
------------------------------------------------------------
[  3] local xx.xx.xx.xx port 40987 connected with yy.yy.yy.yyport 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec  72.0 MBytes  60.3 Mbits/sec

Now using modified read/write buffer size and TCP windows size we get almost the same result as in our test with netio.

Definitely a tool which can be recommended to check your network throughput!

Linux Network Traffic Monitoring

You are running a Linux server and have no possibility to monitor your traffic monthly, daily, weekly etc? Then you really should try vnstat. I like it because it’s:

• easy to install
• easy to use
• collects long term traffic statistics
• doesn’t generate much CPU load

For people who don’t like the shell check out the vnstat PHP frontend.

Installation is esay using Debian Etch:

apt-get install vnstat
vnstat -u -i eth0

For certain virtual servers you have to use a different ethernet interface than “eth0″, e.g. “venet0″:

vnstat -u -i venet0

That’s all. vnstat will now be executed periodically from cron. Some time passed you can check your traffic, like in the example below.

host:~# vnstat -m

eth0  /  monthly

 month         rx      |      tx      |   total
-----------------------+--------------+--------------------------------------
Jan '08     252.40 GB  |     4.17 TB  |     4.41 TB   %:::::::::::
Feb '08     140.07 GB  |     3.96 TB  |     4.10 TB   :::::::::::
Mar '08     152.46 GB  |     4.21 TB  |     4.36 TB   ::::::::::::
Apr '08     150.35 GB  |     4.11 TB  |     4.26 TB   ::::::::::::
May '08     118.78 GB  |     3.53 TB  |     3.65 TB   ::::::::::
Jun '08     144.95 GB  |     4.54 TB  |     4.68 TB   :::::::::::::
Jul '08     157.09 GB  |     4.91 TB  |     5.06 TB   ::::::::::::::
Aug '08     160.96 GB  |     5.01 TB  |     5.17 TB   :::::::::::::::
Sep '08     172.33 GB  |     5.43 TB  |     5.60 TB   ::::::::::::::::
Oct '08     189.69 GB  |     6.12 TB  |     6.31 TB   %:::::::::::::::::
Nov '08     190.89 GB  |     6.52 TB  |     6.71 TB   %::::::::::::::::::
Dec '08     209.59 GB  |     7.35 TB  |     7.55 TB   %:::::::::::::::::::::
-----------------------+--------------+--------------------------------------
estimated   219.94 GB  |     7.71 TB  |     7.93 TB