This is ns-3-allinone, a repository with some scripts to download and build the core components around the ns-3 network simulator. More information about this can be found in the ns-3 tutorial.

If you have downloaded this in tarball release format, this directory contains some released ns-3 version, along with the repository for the NetAnim network animator. In this case, just run the script build.py, which attempts to build NetAnim (if dependencies are met) and then ns-3 itself. If you want to build ns-3 examples and tests (a full ns-3 build), instead type:

./build.py --enable-examples --enable-tests

or you can simply enter into the ns-3 directory directly and use the build tools therein (see the tutorial).

This directory also contains the bake build tool, which allows access to other extensions of ns-3, including the Direct Code Execution environment, BRITE, click and openflow extensions for ns-3. Consult the ns-3 tutorial on how to use bake to access optional ns-3 components.

If you have downloaded this from Git, the download.py script can be used to download bake, netanim, and ns-3-dev. The usage to use basic ns-3 (netanim and ns-3-dev) is to type:

./download.py
./build.py --enable-examples --enable-tests

and change directory to ns-3-dev for further work.