Interpretation of iperf and iperf3 results, especially regarding speed.

After testing my ethernet connection with iperf3, I was wondering if my results are good and what a normal bandwidth should be. Therefore, I started to search for references.

My iperf3 test was done with a CAT6 cable that supports gigabit ethernet. iperf3 was running in TCP mode.

I found the following references and sources.

iperf indicating 940 Mbits/sec using cat 5 cable

~943 megabits per second is the theoretical max throughput you can get with TCP over IPv4 over 1000BASE-T using standard 1500 byte payloads, because of mandatory inter-packet gaps and other protocol overhead. So you're seeing full speeds as expected.

Source:

• https://superuser.com/questions/1417479/iperf-indicating-940-mbits-sec-using-cat-5-cable

Proving the Network is Not the Problem With iperf

From the output above we see that the lowest observed throughput within a one-second interval was 927 Mbps, with an average rate of 939 Mbps. These numbers approach the maximum practical throughput for a 1 Gbps Ethernet link, and strongly suggest that the network is not at fault.

Source:

• https://packetlife.net/blog/2011/feb/28/proving-network-not-problem-iperf/

Iperf testing. What is considered a good result on a Gigabit network?

You should get around 940 Mbps if everything is working properly and you don't have any bottlenecks.

Source:

• https://www.reddit.com/r/HomeNetworking/comments/70sai8/iperf_testing_what_is_considered_a_good_result_on/
• https://www.reddit.com/r/HomeNetworking/comments/70sai8/iperf_testing_what_is_considered_a_good_result_on/dn5kmuy/

Using Iperf for measuring the network speed

The following stats show actual iperf measurements. Measurements were taken on a classic Ethernet hub, a Fast Ethernet switch and a Gigabit Ethernet. Iperf was first started without further options and then with the command iperf -c 192.168.0.20 -w 512k -l 512k.

The measurements were performed between two systems with Intel Core 2 Duo CPU at around 2 GHz. Broadcom NetXtreme Gigabit NICs were used as network cards. The combination of Thinkpad R60 (Windows XP) and Apple Mac Mini C2D 1.83 MHz (Mac OS X Leopard) achieved about 940 MBit/s in the test.

Source:

• http://www.nwlab.net/art/iperf/

• Expected bandwidth
• data transfer rate
• Is my bandwidth ok?
• Are my results good?
• iperf3 expected results
• iperf3 good results example

sudo apt install iperf3

Get server IP:
ifconfig

Server:
iperf3 -s

Client:
iperf3 -c SERVER_IP

iperf3 -s -V

The command above starts iperf3 in server mode. The -s activates the server mode and the -V is for enabling the detailed output (verbose). Other commands can be found with iperf3 help.

iperf3 -s -V > ~/iperf3-log.txt

The command above does the same thing as the one further above, except that it writes the output to the file iperf3-log.txt in the user's home directory in contrast to printing it on the console/ terminal (as the first command does).