iperf3

iperf3 - The Network Speed Measurement Tool

The iperf3 tool is used to measure network speeds via TCP (default) and UDP.

You need 2 nodes in order to test using iperf3.
One node acts as the server (receiver), and the other acts as the client (sender).

Using iperf3

You need both a server node and a client node.

Server Node

To start iperf3 on a node in server mode:

iperf3 -s
# or
iperf3 --server

Then you will use that machine's IP when sending from the client node.

hostname -I | awk '{ print $1 }' # if you don't know the IP

Client Node

On the client node, you specify the server node with -c <ip>.

iperf3 -c 192.168.200.101 -n 1G

• This tests the speed of the network using TCP packets with 1G of data.

iperf3 -c 192.168.200.101 -n 1G -P 128

• This does the same thing, except it uses 128 parallel streams.
  • This is the maximum number of parallel streams you can use in iperf3.

TCP and UDP

By default iperf3 will use TCP packets. When -u is used, it will use UDP packets.
The bitrate is limited for UDP. The default is 1 Mbit/sec for UDP. It's unlimited for TCP/SCTP.

Increasing the bitrate with -b better reflects network speeds with UDP.