Marionnet:
Marionnet is a virtual network laboratory: it allows users to define, configure and run complex computer networks without any need for physical setup. Only a single, possibly even non-networked GNU/Linux host machine is required to simulate a whole Ethernet network complete with computers, routers, hubs, switches, cables, and more. Support is also provided for integrating the virtual network with the physical host network.
It seems like Marionnet would make an effective patch for the TKL Client.