Open Source Python Network Simulators

Build, Design and Test your network in a risk-free virtual environment and access the largest networking community to help. Whether you are studying for your first networking exam or building out a state-wide telecommunications network, GNS3 offers an easy way to design and build networks of any size without the need for hardware.

The Common Open Research Emulator (CORE) is a tool for emulating networks on one or more machines. You can connect these emulated networks to live networks. CORE consists of a GUI for drawing topologies of lightweight virtual machines, and Python modules for scripting network emulation.

An educational network simulator.

NeMo is a high-performance spiking neural network simulator which simulates networks of Izhikevich neurons on CUDA-enabled GPUs. NeMo is a C++ class library, with additional interfaces for pure C, Python, and Matlab.

niab - Network In A Box. Create a virtual lab network inside one machine. A lab can include routers, firewalls, clients and servers connected by a network specified by you. [Linux Network Simulator, UML, user mode linux]

rsim is a simple discrete-event communications network simulator initially developed to test routing protocols for undersea acoustic modem networks. If done well then rsim will eventually be a good replacement for "ns2".