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The Network Simulator, Version 3

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License

This software is licensed under the terms of the GNU General Public License v2.0 only (GPL-2.0-only). See the LICENSE file for more details.

Table of Contents

NOTE: Much more substantial information about ns-3 can be found at https://www.nsnam.org

Overview: An Open Source Project

ns-3 is a free open source project aiming to build a discrete-event network simulator targeted for simulation research and education. This is a collaborative project; we hope that the missing pieces of the models we have not yet implemented will be contributed by the community in an open collaboration process. If you would like to contribute to ns-3, please check the Contributing to ns-3 section below.

This README excerpts some details from a more extensive tutorial that is maintained at: https://www.nsnam.org/documentation/latest/

Building ns-3

The code for the framework and the default models provided by ns-3 is built as a set of libraries. User simulations are expected to be written as simple programs that make use of these ns-3 libraries.

To build the set of default libraries and the example programs included in this package, you need to use the ns3 tool. This tool provides a Waf-like API to the underlying CMake build manager. Detailed information on how to use ns3 is included in the quick start guide.

Before building ns-3, you must configure it. This step allows the configuration of the build options, such as whether to enable the examples, tests and more.

To configure ns-3 with examples and tests enabled, run the following command on the ns-3 main directory:

./ns3 configure --enable-examples --enable-tests

Then, build ns-3 by running the following command:

./ns3 build

By default, the build artifacts will be stored in the build/ directory.

Supported Platforms

The current codebase is expected to build and run on the set of platforms listed in the release notes file.

Other platforms may or may not work: we welcome patches to improve the portability of the code to these other platforms.

Testing ns-3

ns-3 contains test suites to validate the models and detect regressions. To run the test suite, run the following command on the ns-3 main directory:

./test.py

More information about ns-3 tests is available in the test framework section of the manual.

Running ns-3

On recent Linux systems, once you have built ns-3 (with examples enabled), it should be easy to run the sample programs with the following command, such as:

./ns3 run simple-global-routing

That program should generate a simple-global-routing.tr text trace file and a set of simple-global-routing-xx-xx.pcap binary PCAP trace files, which can be read by tcpdump -n -tt -r filename.pcap. The program source can be found in the examples/routing directory.

Running ns-3 from Python

If you do not plan to modify ns-3 upstream modules, you can get a pre-built version of the ns-3 python bindings. It is recommended to create a python virtual environment to isolate different application packages from system-wide packages (installable via the OS package managers).

python3 -m venv ns3env
source ./ns3env/bin/activate
pip install ns3

If you do not have pip, check their documents on how to install it.

After installing the ns3 package, you can then create your simulation python script. Below is a trivial demo script to get you started.

from ns import ns

ns.LogComponentEnable("Simulator", ns.LOG_LEVEL_ALL)

ns.Simulator.Stop(ns.Seconds(10))
ns.Simulator.Run()
ns.Simulator.Destroy()

The simulation will take a while to start, while the bindings are loaded. The script above will print the logging messages for the called commands.

Use help(ns) to check the prototypes for all functions defined in the ns3 namespace. To get more useful results, query specific classes of interest and their functions e.g., help(ns.Simulator).

Smart pointers Ptr<> can be differentiated from objects by checking if __deref__ is listed in dir(variable). To dereference the pointer, use variable.__deref__().

Most ns-3 simulations are written in C++ and the documentation is oriented towards C++ users. The ns-3 tutorial programs (first.cc, second.cc, etc.) have Python equivalents, if you are looking for some initial guidance on how to use the Python API. The Python API may not be as full-featured as the C++ API, and an API guide for what C++ APIs are supported or not from Python do not currently exist. The project is looking for additional Python maintainers to improve the support for future Python users.

ns-3 Documentation

Once you have verified that your build of ns-3 works by running the simple-global-routing example as outlined in the running ns-3 section, it is quite likely that you will want to get started on reading some ns-3 documentation.

All of that documentation should always be available from the ns-3 website: https://www.nsnam.org/documentation/.

This documentation includes:

Working with the Development Version of ns-3

If you want to download and use the development version of ns-3, you need to use the tool git. A quick and dirty cheat sheet is included in the manual, but reading through the Git tutorials found in the Internet is usually a good idea if you are not familiar with it.

If you have successfully installed Git, you can get a copy of the development version with the following command:

git clone https://gitlab.com/nsnam/ns-3-dev.git

However, we recommend to follow the GitLab guidelines for starters, that includes creating a GitLab account, forking the ns-3-dev project under the new account's name, and then cloning the forked repository. You can find more information in the manual.

Contributing to ns-3

The process of contributing to the ns-3 project varies with the people involved, the amount of time they can invest and the type of model they want to work on, but the current process that the project tries to follow is described in the contributing code website and in the CONTRIBUTING.md file.

Reporting Issues

If you would like to report an issue, you can open a new issue in the GitLab issue tracker. Before creating a new issue, please check if the problem that you are facing was already reported and contribute to the discussion, if necessary.

ns-3 App Store

The official ns-3 App Store is a centralized directory listing third-party modules for ns-3 available on the Internet.

More information on how to submit an ns-3 module to the ns-3 App Store is available in the ns-3 App Store documentation.