Files in this directory are imported from NFD (Named Data Networking Forwarding Daemon) project (http://named-data.net/doc/NFD/).
The codebase can be merged with the upstream with the following command:
git subtree pull --prefix=NFD https://github.com/named-data/NFD master
There are several ndnSIM-specific changes to NFD codebase and manual conflict resolution may be required.