TCP Throughput v.s. Round Trip Time (RTT) to Server

We will study how TCP throughput varies with RTT. We will still use iperf3 for this part.

List of public iperf servers

Again, you can get the list of public iperf3 servers here:

What to turn in

You will pick several iperf3 servers (at least 3, ideally located in separate geolocations), and plot bandwidth vs. the RTT to the servers. You can use ping to get the RTT.


Bash/shell script you use to connect and ping the servers. It should at least contain the specific iperf and ping commands you run.


  1. Describe the parameters you use, e.g., length of time to transmit (with -t), which servers you use (and where they are located), and other parameters if you specify any. Note, only the server names should vary, and all other parameters should be fixed.

  2. What mathematical relationship should you expect to see between throughput and RTT? Why?

  3. If what you observe from your plot is not strictly the same as what's shown in the math equation (which is usually the case), then briefly explain what are other possible factors which may affect throughput.