We have two nodes, on one we run iperf as a server, and on the other we’ll run iperf as a client with some arguments to connect to the server and run the tests.

iperf3 is available for Windows with GUI and it can be installed on CentOS using “yum install iperf3” (assuming epel repository is installed).

However my attempts to use iperf3 between Linux and Windows were unsuccessful and here we focus on iperf2.

Also make sure that the ports are not blocked by firewall in any of the nodes. The flow of packets is from client to server. So there is the chance that the iperf server’s firewall block the incoming packets.

Installing iperf2 on CentOS 6

1-  Install the EPEL repository:

# curl -O  http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm

# chmod 755 epel-release-6-8.noarch.rpm

# rpm -ivh epel-release-6-8.noarch.rpm

If after installing EPEL repository you get this error after running yum :

Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again

Run this command to fix it:

# yum upgrade ca-certificates –disablerepo=epel

2- Install iperf2 on CentOS 6.

# yum install iperf

Installing iperf2 on Windows

Download it from : Download it from https://iperf.fr/iperf-download.php At the time of writing this KB the iperf 2.0.5-3 is the latest version of iperf2 for Windows.

It doesn’t need installation and it can be run in command prompt. Either add the path to Windows or change directory

C:\Users\Administrator\Desktop\iperf-2.0.5-3-win32\iperf-2.0.5-3-win32>iperf -s -p 5003

Commands to run iperf in server or client mode

The syntax for both Windows and Linux is the same and it must be run as client in one host and as server in the other.

The following command makes the node as server listening on TCP port 5003

# iperf -s -p 5003

The following command sets the node as client sending TCP packets to server with IP 192.168.155.14 in a period of 90 sec and shows the stat every 10 sec.

# iperf -c 192.168.155.14 -p 5003 -f m -i 10 -t 90

———————————————————————————————-

Example 1 – Linux in client mode and Windows in server mode:

[root@node439 ~]#  iperf -c 192.168.200.81 -p 5003 -f m -i 10 -t 90
————————————————————
Client connecting to 192.168.200.81, TCP port 5003
TCP window size: 0.06 MByte (default)
————————————————————
[  3] local 192.168.200.244 port 40583 connected with 192.168.200.81 port 5003
[ ID]  Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   754 MBytes   632 Mbits/sec
[  3] 10.0-20.0 sec   773 MBytes   649 Mbits/sec
[  3] 20.0-30.0 sec   797 MBytes   669 Mbits/sec
[  3] 30.0-40.0 sec   774 MBytes   649 Mbits/sec
[  3] 40.0-50.0 sec   818 MBytes   686 Mbits/sec
[  3] 50.0-60.0 sec   779 MBytes   653 Mbits/sec
[  3] 60.0-70.0 sec   821 MBytes   689 Mbits/sec
[  3] 70.0-80.0 sec   790 MBytes   663 Mbits/sec
[  3] 80.0-90.0 sec   823 MBytes   690 Mbits/sec
[  3]  0.0-90.0 sec  7129 MBytes   664 Mbits/sec

C:\Users\Administrator\Desktop\iperf-2.0.5-3-win32> iperf -s -p 5003
————————————————————
Server listening on TCP port 5003
TCP window size: 63.0 KByte (default)
————————————————————
[  4] local 192.168.200.81 port 5003 connected with 192.168.200.244 port 40583
[ ID] Interval       Transfer     Bandwidth
[  4]  0.0-90.0 sec  6.96 GBytes   664 Mbits/sec

Example 2 – Windows in client mode and Linux in server mode:

C:\Users\Administrator\Desktop\iperf-2.0.5-3-win32>iperf -c 192.168.200.244 -p 5003 -f m -i 10 -t 90
————————————————————
Client connecting to 192.168.200.244, TCP port 5003
TCP window size: 0.06 MByte (default)
————————————————————
[  3] local 192.168.200.81 port 49237 connected with 192.168.200.244 port 5003
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   748 MBytes   628 Mbits/sec
[  3] 10.0-20.0 sec   723 MBytes   607 Mbits/sec
[  3] 20.0-30.0 sec   751 MBytes   630 Mbits/sec
[  3] 30.0-40.0 sec   737 MBytes   618 Mbits/sec
[  3] 40.0-50.0 sec   798 MBytes   670 Mbits/sec
[  3] 50.0-60.0 sec   822 MBytes   689 Mbits/sec
[  3] 60.0-70.0 sec   727 MBytes   610 Mbits/sec
[  3] 70.0-80.0 sec   804 MBytes   674 Mbits/sec
[  3] 80.0-90.0 sec   754 MBytes   633 Mbits/sec
[  3]  0.0-90.0 sec  6864 MBytes   640 Mbits/sec

[root@node439 ~]# iperf -s -p 5003
————————————————————
Server listening on TCP port 5003 TCP window size: 85.3 KByte (default)
————————————————————
[  4] local 192.168.200.244 port 5003 connected with 192.168.200.81 port 49237
[ ID] Interval       Transfer     Bandwidth [  4]  0.0-90.0 sec  6.70 GBytes   640 Mbits/sec

———————————————————————————————————————

# iperf -c 192.168.200.81 –port 921 –parallel 4 -w 256K -l 64K -t 30

-w (or –window) is for TCP window size (socket buffer size)

–parallel (or -P) is number of parallel client threads to run

-l n [KM] (or –len) set length read/write buffer to n (default 8 KB)

-t (–time) time in seconds to transmit

-f (–format) [kmKM]   format to report: Kbits, Mbits, KBytes, MBytes

-i n (–interval) pause n seconds between periodic bandwidth reports

-s (–server) run in server mode

-c (–client) run in client mode

-p n (–port) set server port to listen on/connect to to n (default 5001)

 

“netperf” and “nuttcp” are also utilities for measuring throughput.