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How to Use iPerf to Identify the Available Bandwidth

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iPerf is a free, third party software that allows admins to test the bandwidth between two Windows machines that are connected to each other. This tool can be used to validate that Zerto is utilizing the entire available bandwidth allocated.


Download & Install iPerf

  1. Navigate to and download iperf for windows 

  2. Install the iPerf tool on both the protected site's ZVM and the recovery site's ZVM.

** In our example, is the ZVM that will be the iPerf client, and will be the iPerf server. There is no significance to which ZVM is used as the iPerf server or client.** 

 Run iPerf on the Recovery site 

  1. Use RDP to connect to the recovery site's ZVM VM.

  2. Open CMD and navigate to the iPerf folder.

  3. Run the following command: iperf3 -s > iPerfServer.txt 6

Run iperf on the Protected site 

  1. Use RDP to connect to the protected site's ZVM VM.

  2. Open CMD and navigate to the iPerf folder.

  3. Use the following command using the ZVM's IP address of the protected site: iperf3 -c > iPerfClient.txt

  4. In our example, the command will be the following: iperf -c > iPerfClient.txt

 Reading the output 

Once the process is done, a text files called " iPerfClient.txt" and "iPerfServer.txt", respectively will be created on the iPerf folder of the ZVMs. The output of those files should be similar to the below outputs:

[ 5] 0.00-1.01 sec 9.88 MBytes 82.3 Mbits/sec
[ 5] 1.01-2.00 sec 10.4 MBytes 87.5 Mbits/sec
[ 5] 2.00-3.00 sec 15.0 MBytes 126 Mbits/sec
[ 5] 3.00-4.00 sec 10.3 MBytes 86.3 Mbits/sec
[ 5] 4.00-5.00 sec 10.2 MBytes 86.0 Mbits/sec
[ 5] 5.00-6.00 sec 14.2 MBytes 120 Mbits/sec
[ 5] 6.00-7.00 sec 10.2 MBytes 85.7 Mbits/sec
[ 5] 7.00-8.00 sec 11.8 MBytes 98.8 Mbits/sec
[ 5] 8.00-9.00 sec 10.5 MBytes 88.3 Mbits/sec
[ 5] 9.00-10.00 sec 12.8 MBytes 107 Mbits/sec
[ 5] 10.00-10.03 sec 176 KBytes 56.1 Mbits/sec
On the above outputs, make sure to note the bandwidth field as this is the current available bandwidth between the sites. On the example from point 10, the maximum bandwidth that has been observed between the ZVMs is 120Mbits/sec.