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 third party components necessary to support two optional ns-3 features: a Python bindings generator named pybindgen and the NetAnim network animator. In this case, just run the script build.py, which attempts to build NetAnim and pybindgen (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

This directory also contains the bake build tool, which allows access to other extensions of ns-3, including the Direct Code Execution environment, and 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, pybindgen, 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.