Are you having a hard time reading the iPerf results? You can read the whole article to find out how to read the iPerf results. If you need help, go visit the community and ask for help from the members of the community.
The result of iPerf should be interpreted based on the iPerf client mode and the results form the iPerf client or server side.
iPerf Client Mode
By default, iPerf in client mode sends data to the server. In this case, the results that you get during the test:
[ 4] 0.00-10.00 sec 466 Mbytes 391 Mbits/sec sender
[ 4] 0.00-10.00 sec 466 Mbytes 391 Mbits/sec receiver
That should be interpreted from the following points:
Sender means the iPerf client, the one that uploads the speed from the iPerf client to iPerf server is measured.
Receiver means iPerf server, the one that downloads the speed from the iPerf client to iPerf server is measured.
For those who start the iPerf client in reverse mode, the data will be sent by the iPerf server and the client will receive it. In such case, here are the results during the test:
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 569 Mbytes 478 Mbits/sec sender
[ 4] 0.00-10.00 sec 569 Mbytes 478 Mbits/sec receiver
It should be interpreted from the following points:
Sender is the iPerf server, the one that uploads the speed from iPerf server to iPerf client is measured.
Receiver is the iPerf client, the one that downloads the speed from iPerf server to iPerf client is measured.
Result from the iPerf client or server side
Default mode test:
Iperf3 – s
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-10.00 sec 0.00 Bytes 0.00 bits/sec sender
[ 5] 0.00-10.00 sec 466 Mbytes 391 Mbits/sec receiver
Iperf3 -c 192.168.0.1
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 466 Mbytes 391 Mbits/sec sender
[ 4] 0.00-10.00 sec 466 Mbytes 391 Mbits/sec receiver
During this test iPerf, client was the sender and in the results you are able to see:
From client logs:
Sender is the iPerf client, the one that uploads the speed from the iPerf client to iPerf server is measured.
Receiver is the iPerf server, the one that downloads the speed on the iPerf server from iPerf client is measured.
From server logs:
Sender is the iPerf client, the one that uploads the speeds from iPerf client to iPerf server is measured.
Receiver is the iPerf server, the one that downloads the speed on the iPerf server from iPerf client is measured.
Reverse mode test:
iPerf3 -s
[ ID] Interval Transfer Bandwidth
[ 5] 0.00-10.01 sec 569 MBytes 477 Mbits/sec sender
[ 5] 0.00-10.01 sec 0.00 Bytes 0.00 bits/sec receiver
Iperf3 -c 192.168.0.1 -R
[ ID] Interval Transfer Bandwidth
[ 4] 0.00-10.00 sec 569 Mbytes 478 Mbits/sec sender
[ 4] 0.00-10.00 sec 569 Mbytes 478 Mbits/sec receiver
During this test, iPerf server was a sender and in the results you can see:
From the client logs:
Sender is the iPerf server, the one that uploads the speed from the iPerf server to iPerf client is measured.
Receiver is the iPerf client, the one that downloads the speed on the iPerf client from the Iperf server is measured.
From the server logs:
Sender is the iPerf server, the one that uploads the speed from the iPerf server to the iPerf client is measured.
Receiver is the iPerf client, the one that downloads on the iPerf client from iPerf server is measured.
For better understanding about the iPerf results, here is an example for you.
Results:
Connecting to host 10.0.1.192, port 5201
[ 5] local 10.0.1.51 port 50191 connected to 10.0.1.192 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-1.00 sec 9.54 MBytes 80.0 Mbits/sec
[ 5] 1.00-2.00 sec 11.3 MBytes 94.7 Mbits/sec
[ 5] 2.00-3.00 sec 11.3 MBytes 94.5 Mbits/sec
[ 5] 3.00-4.00 sec 11.2 MBytes 94.2 Mbits/sec
[ 5] 4.00-5.00 sec 11.2 MBytes 93.6 Mbits/sec
[ 5] 5.00-6.00 sec 11.3 MBytes 94.6 Mbits/sec
[ 5] 7.00-8.00 sec 11.2 MBytes 94.2 Mbits/sec
[ 5] 9.00-10.00 sec 11.1 MBytes 93.5 Mbits/sec
[ 5] 1.00-2.00 sec 11.3 MBytes 94.7 Mbits/sec
[ 5] 1.00-2.00 sec 11.2 MBytes 94.3 Mbits/sec
[ ID] Interval Transfer Bitrate
[ 5] 0.00-10.00 sec 111 MBytes 92.8 Mbits/sec – sender
[ 5] 0.00-10.05 sec 110 MBytes 92.0 Mbits/sec – receiver
According to the example, it can be concluded that:
The iPerf’s Transfer column is in MebiBytes: 1,048,576’s of 8-bit Bytes.
The iPerf’s Bitrate column is in megabits: 1,000,000’s of 1-bit bits.
94 Mbits per second is the max rate that you are able to get for TCP/IP throughput on 100 megabit Ethernet with the standard size frames. You should be seeing 942 megabits per second if it was gigabit Ethernet.
The results above show that you have only established a 100 megabit link between the two Macs. Please check your wiring in order to make sure that you have all 4 pairs, with the right pinout on both ends, and make doubly sure you have not split a pair. Aside from that, it is better for you to double check your USB Ethernet dongle to make sure it’s gigabit. A lot of them are only 10/100. In addition, please make sure both Macs say its gigabit Ethernet and make sure the switch thinks both ports have negotiated gigabit.
The example above was posted by Kamil Maciorowski on Super User. The one who explains about the result is called Spiff. Kamil Maciorowski expects 600 to 700 megabits per second and Spiff is not sure why he expects that amount because Macs have been able to saturate gigabit Ethernet at 942 mbps on iPerf since around the 1GHz PPC G4 Macs in 2001. It means anything less and you have the faulty wiring that does not meet the Cat5 spec or is longer than 100m. For more information about the thread, please visit a forum called Super User and find the one with them.
