Create your own traffic shaping test with Glasnost

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What applications can you write tests for?

Before we describe how to create a new Glasnost test, let us point out two important things about Glasnost tests.
First, Glasnost currently only supports testing application traffic that uses TCP; at this time UDP is not supported.
Second, our current implementation of Glasnost uses throughput as a measure for performance. This means that Glasnost detects traffic differentiation that affects flow throughput (throttling or blocking). Hence, Glasnost is most suitable to test application traffic that is bandwidth-intensive, such as P2P filesharing, HTTP downloads, etc. Testing for latency-sensitive applications (e.g., Skype, online games) that may be shaped by delaying packets is currently not supported.

For accurate detection of traffic shaping, our algorithm assumes:
  1. The application flows are long (typically longer than 10 seconds) to allow for an accurate throughput estimation.
  2. The throughput of the application flow is not limited by the application. Applications that use a large download work best (e.g., BitTorrent, Web download, etc.), while for example VoIP applications typically send data at a constant bitrate, which is not suitable for Glasnost.

Please mind these assumptions when creating your own Glasnost test.

The 4 steps to create a new Glasnost test

This is a brief introductory tutorial to trace-emulate. We also provide a more detailed example here. For more details on how Glasnost tests work, please read our NSDI 2010 paper.

1. Download the test generation tool

You can download our trace-emulate tool by clicking on this link.
Trace-emulate is written in python. You will need a python environment installed on your machine to run it. Some systems (like MacOS and Linux) have python installed by default. To download and install python for your operating system, please visit the official Python website.

A detailed description of the parameters of trace-emulate can be found below.

2. Collect a packet trace of a network application you suspect your ISP is differentiating

To create a new test, you have to collect a pcap packet trace of your application's traffic. There are free programs available to do this, e.g., Tcpdump and Wireshark. We added detailed descriptions on how to collect a trace below:

Please note that for the moment Glasnost only supports traffic differentiation detection for applications that use TCP.

3. Run trace-emulate on the collected trace

On the command line, type something like this:

python <yourPcapTraceFile>

Replace <yourPcapTraceFile> with the name of the file that contains your trace.

4. Upload the generated test file(s) to Glasnost and run the test

At this point, trace-emulate will produce a number of test files, one for each TCP connection contained in the trace. You can upload one of these files to Glasnost through this Web page and run the test.

Important advice when generating a Glasnost test

Privacy: A trace of your network traffic may contain sensitive information such as passwords, user names, or credit card numbers. The generated tests will contain this information as well.
Make sure the generated tests do not contain information you are uncomfortable giving away: Do not generate tests from traffic that might contain sensitive information and inspect the generated test files and search for potential sensitive information that might be contained.

Creating accurate tests: In order for trace-emulate to correctly generate a test, you should obey the following three points:


Trace-emulate in detail

Usage: python [options] <pcap_file>

Replace <pcap_file> with the name of your trace file. You can also use "–" to make trace-emulate read from the standard input. Trace-emulate supports reading from compressed gzip files (.gz), just make sure that the files have the .gz extension.

Trace-emulate accepts the following command line options:


In case you have questions about this tool or our research, please contact us: broadband @at@ mpi-sws mpg de

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