CDNsim is a GNU/LINUX simulation tool for CDNs, written in C++ (core) and python (GUI wizard). It models: redirection policies, cache policies, TCP/IP, batch simulations, statistics extraction and more. CDNsim is uses the OMNet++ library
pyomnet provide an object-oriented way to define the network topology.
It's a good way to illustrate network in an abstract way.
pyomnet could generate the NED scenario and configuration(latter) for OMNeT++ simulation tool.