Tag Archives: speed-test

Stress testing my router to know max transfer speed over WiFi/LAN

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https://www.speedtest.net/ is great tool for learning about your internet connection speed.

If you are in a local environment, how do you figure out available bandwidth? Use cases: copying large files from one internal machine to another internal machine? Or running a local streaming service.

You can usehttps://iperf.fr/. You need two machines capable or running iperf3.

To test WiFi speed, at least one of connected via Wi-Fi. Both can also be connected by WiFi (worst case). My recommendation is to test in both cases.

  • Install iperf3 on both machines A and B.
  • Run iperf3 -s on machine A or use iperf3 -s -D to keep it running as daemon. Handy if you plan to test periodically.
  • Run iperf3 -c <ip_of_A> on machine B.

Sample output

Here is sample output at my home when both devices are connected by WiFi.

On a machine with IP 191.168.1.142, I run iperf3 in server mode.

$ iperf3 -s -D

Then on second machine

$ iperf3 -c 192.168.1.142
Connecting to host 192.168.1.142, port 5201
[  5] local 192.168.1.131 port 38888 connected to 192.168.1.142 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  12.8 MBytes   107 Mbits/sec    0    124 KBytes       
[  5]   1.00-2.00   sec  13.2 MBytes   111 Mbits/sec    0    124 KBytes       
[  5]   2.00-3.00   sec  13.1 MBytes   110 Mbits/sec    0    124 KBytes       
[  5]   3.00-4.00   sec  13.6 MBytes   114 Mbits/sec    0    124 KBytes       
[  5]   4.00-5.00   sec  13.0 MBytes   109 Mbits/sec    0    124 KBytes       
[  5]   5.00-6.00   sec  12.6 MBytes   106 Mbits/sec    0    124 KBytes       
[  5]   6.00-7.00   sec  11.2 MBytes  94.4 Mbits/sec    0    124 KBytes       
[  5]   7.00-8.00   sec  10.4 MBytes  87.0 Mbits/sec    0    124 KBytes       
[  5]   8.00-9.00   sec  13.0 MBytes   109 Mbits/sec    0    124 KBytes       
[  5]   9.00-10.00  sec  13.1 MBytes   110 Mbits/sec    0    124 KBytes       
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec   126 MBytes   106 Mbits/sec    0            sender
[  5]   0.00-10.01  sec   126 MBytes   105 Mbits/sec                  receiver

iperf Done.

Here we go. I have some idea how fast I can transfer data between two computers on my local network.