For new versions, check https://github.com/Darkkey/javaNetSim
javaNetSim (Java Network Simulator) - it's a fork of a project jFirewallSim. The main goal of javaNetSim is creating a software to simulate various TCP/IP networks based on Ethernet, WiFi, PPP, etc...
ROOTSNNS is a set of C++ classes which allows one to use the Stuttgart Neural Network Simulator kernel (ansi-C) within the ROOT, a data analysis package. Multiple ANNs can be built, trained, and tested, while results and ANN performance can be saved.