In our connected world, it is good to now in what shape our network is, from the end-user perspective. While we may not be able to change the network environment, knowing it’s limits is useful. If you have to upload a large ISO image to the server, you can decide to go grab a coffee after the transfer starts, if you know your corporate network will not be able to transfer that much data in the next hour. This is of course just a random fictional nightmare, but knowing the network throughput means knowing how our systems will perform regarding network communication, and have another known area when debugging.
iperf is a handy application allowing easy client-server setup, and able to measure network bandwidth, jitter, and packet loss ratio. While it has many options to tweak our measurements, we’ll use only the defaults to test the application’s work.
In this tutorial you will learn:
- How to install
iperfon Red Hat Enterprise Linux 8. - How to test network bandwidth to the system.
- How to test network bandwidth from the system.
Software Requirements and Conventions Used
| Category | Requirements, Conventions or Software Version Used |
|---|---|
| System | Red Hat Enterprise Linux 8 |
| Software | iperf3-3.5-1 |
| Other | Privileged access to your Linux system as root or via the sudo command. |
| Conventions |
# – requires given linux commands to be executed with root privileges either directly as a root user or by use of sudo command$ – requires given linux commands to be executed as a regular non-privileged user |
How to install iperf on RHEL 8 step by step instructions
iperf3 is in the default repositories after enabling Subscription Management repositories, so installing it is quite easy.
-
dnf install iperf3
- To test the network using our lab machine as a server (the target), we start it in server mode:
$ iperf3 -s ----------------------------------------------------------- Server listening on 5201 -----------------------------------------------------------
Note that
iperf3is listening on another port by default, as earlier versions (the client in this test included) use port5001.And from the remote testing machine, we start the test (we need to specify the port as it is non-default to iperf):
$ iperf -c 192.168.1.14 -p 5201 ------------------------------------------------------------ Client connecting to 192.168.1.14, TCP port 5201 TCP window size: 85.0 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.1.7 port 55366 connected with 192.168.1.14 port 5201 write failed: Connection reset by peer [ ID] Interval Transfer Bandwidth [ 3] 0.0- 5.5 sec 888 MBytes 1.36 Gbits/sec
- To test network using our lab machine as a client (the source), we start
iperfin server mode on the remote machine (this time in a different network, usingiperf3on the other side too):$ iperf3 -s ----------------------------------------------------------- Server listening on 5201 -----------------------------------------------------------
And run the test from our lab machine:
$ iperf3 -c 192.168.1.2 Connecting to host 192.168.1.2, port 5201 [ 5] local 192.168.1.14 port 51736 connected to 192.168.1.2 port 5201 [ ID] Interval Transfer Bitrate Retr Cwnd [ 5] 0.00-1.00 sec 3.21 MBytes 26.9 Mbits/sec 0 160 KBytes [ 5] 1.00-2.00 sec 3.48 MBytes 29.2 Mbits/sec 0 301 KBytes [ 5] 2.00-3.00 sec 3.79 MBytes 31.8 Mbits/sec 0 448 KBytes [ 5] 3.00-4.02 sec 3.04 MBytes 25.0 Mbits/sec 0 380 KBytes [ 5] 4.02-5.01 sec 3.36 MBytes 28.6 Mbits/sec 0 434 KBytes [ 5] 5.01-6.00 sec 2.11 MBytes 17.8 Mbits/sec 0 332 KBytes [ 5] 6.00-7.00 sec 2.24 MBytes 18.7 Mbits/sec 0 351 KBytes [ 5] 7.00-8.00 sec 1.06 MBytes 8.88 Mbits/sec 0 368 KBytes [ 5] 8.00-9.00 sec 3.17 MBytes 26.6 Mbits/sec 0 372 KBytes [ 5] 9.00-10.00 sec 2.17 MBytes 18.2 Mbits/sec 0 372 KBytes - - - - - - - - - - - - - - - - - - - - - - - - - [ ID] Interval Transfer Bitrate Retr [ 5] 0.00-10.00 sec 27.6 MBytes 23.2 Mbits/sec 0 sender [ 5] 0.00-10.00 sec 25.8 MBytes 21.7 Mbits/sec receiver iperf Done.
Note that we didn’t specify the port, as in this case there is
iperf3on both sides, with ports defaulting to5201.And we can see the results more verbose on the server side as well:
Accepted connection from 192.168.1.14, port 51734 [ 5] local 192.168.1.2 port 5201 connected to 192.168.1.14 port 51736 [ ID] Interval Transfer Bandwidth [ 5] 0.00-1.00 sec 2.63 MBytes 22.0 Mbits/sec [ 5] 1.00-2.00 sec 2.92 MBytes 24.5 Mbits/sec [ 5] 2.00-3.00 sec 2.80 MBytes 23.5 Mbits/sec [ 5] 3.00-4.00 sec 2.80 MBytes 23.5 Mbits/sec [ 5] 4.00-5.00 sec 2.99 MBytes 25.1 Mbits/sec [ 5] 5.00-6.00 sec 2.75 MBytes 23.1 Mbits/sec [ 5] 6.00-7.00 sec 1.50 MBytes 12.6 Mbits/sec [ 5] 7.00-8.00 sec 1.80 MBytes 15.1 Mbits/sec [ 5] 8.00-9.00 sec 2.60 MBytes 21.8 Mbits/sec [ 5] 9.00-10.00 sec 2.77 MBytes 23.2 Mbits/sec [ 5] 10.00-10.12 sec 279 KBytes 19.5 Mbits/sec - - - - - - - - - - - - - - - - - - - - - - - - - [ ID] Interval Transfer Bandwidth [ 5] 0.00-10.12 sec 0.00 Bytes 0.00 bits/sec sender [ 5] 0.00-10.12 sec 25.8 MBytes 21.4 Mbits/sec receiver
We can see that in the first testing case the two systems have much better connection then in the last one. We can also see how ports and outputs differ depending on iperf version, and we verified that our tool is working in both server and client mode as well.