Iperf- Determine Bandwidth of the Link

Iperf Tool


Iperf is the network tool which is used to verify the wired and wireless link bandwidth and throughput. The tool is helpful to check the health of the link, common thing people do is blame service providers when they face any issue but it’s possible that problem could be at customer premises. End-to-end status can be checked for both TCP and UDP will be discussed shortly in the below section.
Iperf is available for windows and Linux and can be easily available on internet for free of cost. It is an executable file not requires any installation just directly run it as a server and client means two systems are necessary for the process with the iperf running as a server in one machine and client on second machine.

Wikipedia Definition
Iperf is a commonly used network testing tool that can create TCP and UDP data streams and measure the throughput of a network that is carrying them. Iperf is a modern tool for network performance measurement written in C++.
Iperf allows the user to set various parameters that can be used for testing a network, or alternately for optimizing or tuning a network. Iperf has a client and server functionality, and can measure the throughput between the two ends, either unidirectonally or bi-directionally. It is open source software and runs on various platforms including linux, unix and windows. It is supported by the National Laboratory for Applied Network Research.
When used for testing udp capacity, Iperf allows the user to specify the datagram size and provides results for the datagram throughput and the packet loss.
When used for testing tcp capacity, Iperf measures the throughput of the payload. One thing to note is that Iperf uses 1024*1024 for Megabytes and 1000*1000 for Megabits. There is a GUI front end available called jperf.
Typical Iperf output contains a timestamped report of the amount of data transferred and the throughput measured.
Iperf is significant as it is a standardized tool that can be run over any network and output standardized performance measurements. Thus it can be used for comparison of wired and wireless networking equipment and technologies in an unbiased way. As it is open source, the measurement methodology can be scrutinized by users.



Sequential flow 

Figure-1 Infrastructure of the network

 IP configuration in windows

1. Connect host A and Host B with an Ethernet Cross cable (100 Mbps).
2. Assign IP addresses to host A and Host B.

Figure-2 Assigning IP to Host A and Host B

check bandwidth of link

check bandwidth of link

Host A IP Configuration Host B IP Configuration
3. The location of Iperf.exe is C drive.

Figure-4 iperf.exe location


4. Run Iperf as a Server on Host A as shown in the figures below.

Figure-5 Open command prompt on Host A


Figure-6 Run server process of Iperf on Host A

5. Now Host A working as a Server.


Figure-7 Iperf Process running on Host A


Iperf Process

Iperf Process

6. Server is prepared to listen for client connection, which will be in that case is Host

B running the client process as shown in the figures below.

Figure-8 Iperf.exe location on Host B (Client)




Figure-9 Check the status of server


Run dialog

Run dialog

Figure-10 Open the command prompt on client

Figure-11 Running Iperf process on Host A to connect Iperf Server


NOTE: To connect client with server, Ip address should be provided in correct format, host A must running the server iperf process to listen for the client connection or connections on port 5001 by default.
7. Figure-11 displaying the result of default file transfer from client machine (Host B) to server machine (Host A). Client machine using port 1063 to connect on the listening port of server which is by default port 5001. The link bandwidth is 94.4 Mbits/sec Client transfers 113 Mbytes file to server as shown in the figure.
Figure-11 Transferring word document from client to server

Figure-12 transferring audio Mp3 format file from client to server

Figure-13 transferring Video Avi format file from client to server

Figure-14 Transferring movie file by establishing parallel connection with server

Figure-15 Messages on the server machine


8. To check the summary of commands use help.

Figure-16 Summary of commands in Iperf

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