Unless a custom branch of NS-3 is used (recommended), ndnSIM requires a number of patches to be applied on NS-3.
Patches are in patches/ folder

For more information, refer to documentation in doc/ or on http://irl.cs.ucla.edu/ndnSIM/

Depending on which base NS-3 is used, you may need to rescan python binding

./waf --apiscan=ndnSIM