This is ns-3-allinone. If you have downloaded this in tarball release format, this directory contains some released ns-3 version, along with 3rd party components necessary to support all optional ns-3 features, such as Python bindings and the Network Animator. In this case, just run the script build.py; all the components, plus ns-3 itself, will thus be built. This directory also contains the bake build tool, which allows access to several additional modules including the Network Simulation Cradle, Direct Code Execution environment, and click and openflow extensions for ns-3. If you have downloaded this from mercurial, the download.py script will 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 and cd into ns-3-dev for further work. Consult the bake documentation on how to use bake to access optional ns-3 components.