I'm looking for an open-source network simulator. I'd want to simulate different topologies, ie: Bus, Star, Ring, Tree, etc...
It doesn't matter for me to simulate a Cisco product, only interconnecting nodes, and generic switches/routers, and show behaviour of different topologies, etc. It could be nice that such a software didn't need one entire day of studying its documentation to use it.
The software should preferably run on Linux.