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When it comes to iPerf, everyone must know that it is a command used to test network performance. iPerf is an open source network performance testing tool developed by the University of Illinois. It can be used to test the performance of TCP or UDP connections between network nodes (including loopback), including bandwidth, jitter and packet loss rate, where jitter and packet loss rate are suitable for UDP testing, and bandwidth testing is suitable for TCP and UDP.
Generally speaking, the bandwidth test adopts UDP mode test, because the limit bandwidth, path delay, and packet loss rate can be measured in UDP mode, and these test items will be printed out in the bandwidth test report. When testing, first use the theoretical bandwidth of the link as the data transmission rate to test, for example, the theoretical bandwidth of the link from the client to the server is 1000Mbps, first use -b 1000M to test, and then according to the test results (including Actual bandwidth, delay jitter and packet loss rate), and then use the actual bandwidth as the data transmission rate to test, you will find that the delay jitter and packet loss rate are much better than the first time, repeat the test several times, you can get a stable actual bandwidth.
iPerf works based on the server-client mode. Therefore, to use iPerf to test bandwidth, you need to establish a server (for discarding traffic) and a client (for generating traffic). The iPerf server or client uses the same command, but the options to start the command are different.

Key Features of iPerf

TCP

Measure network bandwidth
Report size and observations of MSS/MTU values
Support for TCP window values ​​via socket buffering
Multithreading is supported when P threads or Win32 threads are available. Client and server support simultaneous multiple connections

UDP

Clients can create UDP streams of specified bandwidth
Measure packet loss
Measurement delay
Multicast support
Multithreading is supported when P threads are available. Client and server support simultaneous multiple connections (does not support Windows)

iPerf installation

To install IPerf, you can download it for different operating systems at https://iperf.fr/iperf-download.php. It is recommended to download the iPerf2 version. Since iPerf3 cannot support multi-process download, it is more troublesome to perform multi-process testing. The specific command can be modeled as follows:
Enable multithreading on the server:
iperf3 -s -p 5101&; iperf3 -s -p 5102&; iperf3 -s -p 5103 &
The client enables multithreading:
iperf3 -c hostname -T s1 -p 5101 &;
iperf3 -c hostname -T s2 -p 5102 &;
iperf3 -c hostname -T s3 -p 5103 &;
It can be seen that iPerf3 multi-threading is actually opening multiple ports for testing, which is troublesome, so it is recommended to download iperf2.

1. For the windows version of iPerf, directly copy the decompressed iperf.exe and cygwin1.dll to the %systemroot% directory
2. For the linux version of iPerf, please use the following command to install rpm -ivh iperf-.rpm # iPerf Startup Test

The iPerf test requires that the server side and the client side execute commands respectively to start

Server

iperf -s -p [端口]

client

iperf -c [server IP]
Note: iPerf tests the bandwidth of the TCP protocol by default. If you need to test the bandwidth of UDP, you need to add the -u option
The following is a simple test example:

1. Bandwidth test for TCP:

iperf -s -p 3389
iperf -c 10.104.17.84 -p 3389 -t 30 -i 1

Introduction of common indicators:

-c: client mode, followed by server ip
-p: followed by the port the server is listening on
-i: Set the time interval for bandwidth reporting, in seconds
-t: Set the duration of the test, the unit is seconds, the default is 10s if not set
-w: Set the size of the tcp window, generally do not need to be set, the default can be

To test multi-threaded TCP, add the -P parameter to the client to test the multi-threaded TCP performance
Server and client for TCP bandwidth test

2. Bandwidth test for UDP:

iperf -s -p 3389 -u
iperf -c 10.104.17.84 -p 3389 -i 1 -u -b 2000M

Introduction of common indicators:

-c: client mode, followed by server ip
-p: followed by the port the server is listening on
-i: Set the time interval for bandwidth reporting, in seconds
-t: Set the duration of the test, the unit is seconds, the default is 10s if not set
-b: Set the sending bandwidth of udp, in bit/s
UDP bandwidth test on server and client

iPerf common options