I'm using Iperf3 on 2 machines and actually I'm running 2 instances of Iperf3, one to generate traffic with high priority and the other generates traffic with low priority.

I would like to generate a graph of both traffics, but the problem that I don't know when exactly the second traffic started. and Iperf3 doesn't show timestamps.

I was searching for wireshark dissector but I couldn't find something useful

I tried to run tcpdump and get results on file then open it with wireshark but it gave me un realistic results,

5Mbps instead of 35Mbps

Please help me in this issue. Thanks in advance.


If you get a tcpdump of this traffic, you can differentiate the two streams in Wireshark by port number or QoS marking depending on how these two traffic types are generated.

Take those display filters and use them to graph bits/tick in IO Graph. You should have two lines, one for each traffic type. If you don't like the way IO Graph looks, you can export the data in CSV format using the Copy button and import into Excel or another tool.

Wireshark IO Graph

The picture doesn't have the graph lines due to an issue with my Wireshark. Change the port numbers to what your ports numbers are.

  • Thanks Kary. but what about the rate I'm getting in IO Grah, the graph shows me that at one tick for example that the rate is 6000000 bits/sec which if we convert it to Mbps gives us about 6Mbps. while at that exact moment the rate that iperf reported was 35.6 Mbps What's the reason
    – Alberto
    Apr 24 '15 at 12:47
  • Tough to say without being able to look at the data. It's possible they use different scopes when aggregating data into averages, but 6 vs 35.6 is a big difference. I've certainly seen differences in numbers across different tools but nothing like that unless there's an error being made somewhere. I've found Wireshark and IO Graph to be reliable (when I can get it to actually show me the graphs, that is). Is it possible iperf was giving you the average tput from the beginning of the transfer up to that moment instead of the tput at that exact moment?
    – karyhead
    Apr 24 '15 at 16:34

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