Examples for using kodo with ns-3
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README.rst

Introduction

This repository demonstrates how to use the Kodo erasure coding library (http://steinwurf.com/kodo/) in various ns-3 examples.

A valid Kodo license is required if you wish to use this project. Please request a license by filling out the license request form.

Kodo is available under a research- and education-friendly license, you can see the details here.

If you try to configure without a valid license, then you will get an error!

ns-3 (http://nsnam.org) is a discrete-event network simulator, targeted primarily for research and educational use. ns-3 is licensed under the GNU GPLv2 license.

Buildbot status

Using Kodo in an ns-3 example

The examples in this repository will be installed to the examples/kodo subfolder of your ns-3 folder. We will also build the Kodo-C shared library which will be installed in the same folder together with the required header files. The examples will dynamically link to the shared library.

Getting Started

As a first step, you need ns-3 installed on your development machine. You may find lots of information about this on the ns-3 webpage:

http://www.nsnam.org/wiki/index.php/Installation

On Ubuntu/Debian, you need to install the following packages:

sudo apt-get install g++ python mercurial git-core

In the following, we will clone ns-3 to the ~/ns-3-dev folder and we will clone the kodo-ns3-examples to the ~/kodo-ns3-examples folder. You may use different folders, but the two folders must be separate, i.e. one cannot be the subfolder of the other.

Installing ns-3

First clone the ns-3 repository (we start from the home folder, so it will be cloned to ~/ns-3-dev):

cd ~
hg clone http://code.nsnam.org/ns-3-dev/

This command will download the ns-3 simulator to your computer into the ns-3-dev folder (this may take a few minutes).

Go to this freshly cloned folder:

cd ns-3-dev

Our aim is to make the examples compatible with the latest ns-3 revision. If you experience any issues with the latest revision, then you can switch to the latest supported revision (this step is optional):

hg checkout 12799

Our build system automatically tests the examples with the latest supported revision of ns-3. This revision is specified in our buildbot.py script.

Configure the ns-3 project (it is important to also enable the examples):

python waf configure --enable-examples

This will output a whole bunch of information about the enabled modules based on the availability of tools and libraries installed on your computer.

Now we build the ns-3 libraries and examples:

python waf build

Installing the Kodo examples to ns-3

After building ns-3, you can switch to the kodo-ns3-examples repository. We will clone this repository to the ~/kodo-ns3-examples folder:

cd ~
git clone git@github.com:steinwurf/kodo-ns3-examples.git

Configure this project:

cd kodo-ns3-examples
python waf configure

The waf configure command ensures that all dependencies are downloaded (by default, waf will create a folder called bundle_dependencies to store these libraries).

You must have a valid Steinwurf license to download the fifi and kodo dependencies, otherwise you will get a git error when you execute the configure command!

Now we build the kodo-c shared library and we install the examples and all the required files to the ~/ns-3-dev/examples/kodo folder:

python waf build install --ns3_path="~/ns-3-dev"

The --ns3_path option is used to specify your ns-3 folder (you can change this if your ns-3 is located elsewhere).

Building the Kodo examples in ns-3

After the install step, you can switch back to your ns-3 folder:

cd ~/ns-3-dev

You can follow the normal ns-3 workflow to build our examples. The ns-3 waf will automatically find the new examples in ~/ns-3-dev/examples/kodo:

python waf build

We have the following examples:

  • kodo-wired-broadcast: This example demonstrates broadcasting packets with RLNC from a transmitter to N receivers with the same erasure channel.
  • kodo-wifi-broadcast: This example demonstrates broadcasting packets with RLNC to N receivers over an IEEE 802.11b WiFi channel.
  • kodo-recoders: This example shows the gain of RLNC with recoding in a 2-hop line network consisting of an encoder, N recoders and a decoder with different erasure rates. Recoding can be turned on or off and the erasure rates can be modified by command-line options.

You can find more details about each example in their respective source files. There you can also check how to change the simulation parameters like the packet-, field- and generation sizes.

You can run the examples with the usual ns-3 run commands:

python waf --run kodo-wired-broadcast
python waf --run kodo-wifi-broadcast
python waf --run kodo-recoders

Most of the examples will print out how the decoding matrix changes with each combination packet. You will see if a received packet is linearly dependent or not. You will also see when the decoding process is completed and how many transmissions were required.

Adding your own simulation

At this point, you might want to add your own simulation that uses kodo. It is recommended to create a new program by copying one of the kodo examples. The examples are installed in ~/ns-3-dev/examples/kodo, so we will go to that folder and make a copy kodo-wifi-broadcast.cc to create a new simulation called my-simulation.cc (you can choose any name here):

cd ~/ns-3-dev/examples/kodo
cp kodo-wifi-broadcast.cc my-simulation.cc

To build an executable from the my-simulation.cc source file, we have to define a new program in ~/ns-3-dev/examples/kodo/wscript. Open this file in your text editor, and add the following lines at the end (be careful with the indentation since this is a Python script):

obj = bld.create_ns3_program('my-simulation',
                             ['core', 'applications', 'point-to-point',
                              'point-to-point-layout', 'internet', 'wifi'])
obj.source = 'my-simulation.cc'
set_properties(obj)

After this change, the ns-3 waf will detect the new example and you will be able to run it from the ~/ns-3-dev folder as usual:

cd ~/ns-3-dev
python waf --run my-simulation

Now you can expand your custom simulation as you like. If you use additional ns-3 modules, then you need to add them in the wscript (most likely, you will get a build error if you are missing a module).

If your simulation has multiple source files (*.cc files), then you can add these in the wscript like this:

obj.source = ['my-simulation.cc', 'source2.cc', 'source3.cc']

Warning: If you install the kodo ns-3 examples again with this command:

cd ~/kodo-ns3-examples
python waf build install --ns3_path="~/ns-3-dev"

then the example source files and the wscript will be overwritten in the ~/ns-3-dev/examples/kodo folder, so it is recommended to create a backup if you modified any of these files.

You can also create a separate folder for your custom simulation to avoid this problem. For example, you can create the ~/ns-3-dev/examples/my-simulation folder and copy the include and lib folders from ~/ns-3-dev/examples/kodo.

Tutorial

Our Kodo-ns3 tutorial provides a more comprehensive description of these examples. For each example, we verify known results to validate our model and provide parameters to the user for modifying them.

Comments, Feedback, Bugs & Questions

If for some reason your project does not build or you have any other issues or questions related to the project after precisely following the build instructions, please feel free to contact us through our developers mailing list hosted at Google Groups:

If you make new examples or use the examples provided here for your research, please let us know!

We would be happy to add links to your work or potentially include them as new examples!

Please follow these guidelines for posting on the mailing list to make the workflow efficient and simple:

  • Before submitting questions about building the project, please make sure that you have followed the procedure described above
  • Before submitting your question, please check the mailing list to see if it has been already answered, most of the basic questions tend to be the same
  • Do not reply to previously opened threads if they are not related to your question
  • If your question is new, you may open a new mail thread
  • When stating your question, be clear about your objectives. For simulations, please tell us what you want to simulate in terms of system model, assumptions, parameters and consider the limitations of ns-3 and/or Kodo. At first, try to provide a concise general description. Later, you can add details if you think that those are relevant to your question.
  • If you have followed the previous steps and still want to report an error, please do the following:
    1. In your e-mail, indicate us the failure problem and when does it occur. Indicate the type of problem (e.g. if it is compiler error or a segmentation fault or something else). Also include your OS, compiler waf, python and ns-3 version.
    2. Attach a printscreen or a .txt log file posting the complete output of the command of procedure that gives the error. .
    3. If your error is related with a source file, please include it as well in your report.
  • Disclaimer: We will not correct your source code, but just provide you guidelines to do so :)

Also, feel free to tell us what we should add to improve the examples and the tutorial!

Finally, ns-3 users have their mailing list so you can ask questions strictly related to ns-3 there following their mail posting rules.