GNS3 vs NetSim by Tetcos

GNS3 is free, open-source software for emulating, configuring, testing, and troubleshooting virtual and real networks. Its graphical client works with a virtual machine, and servers can run locally or remotely. Users can combine emulated devices running actual images with simulated devices, including a built-in layer 2 switch. It supports appliances from vendors such as Cisco, Brocade, Cumulus Linux, and HPE, as well as Docker, QEMU-based appliances, VMware, VirtualBox, Hyper-V, and connections to real networks. The GNS3 Marketplace offers preconfigured appliance templates with recommended settings. It runs on Windows, macOS, and Linux; documentation recommends the GNS3 VM for most Windows and macOS setups and complex topologies. Users must supply their own Cisco IOS images. There are no monthly or yearly license fees, and device capacity depends in practice on the host computer’s CPU and memory. GNS3 is used for networking education, certification practice, proofs of concept, demonstrations, and interoperability testing. A server has no authentication enabled by default and should be restricted at the network level.

NetSim by Tetcos is a packet-level, discrete-event simulator and emulator for wired and wireless communication networks. It models end-to-end 5G and 6G systems with gNB, UE, 5G Core, MIMO, beamforming, network slicing, and configurable propagation. Each 5G stack layer includes C source code that users can modify for custom protocols, while an external Python interface supports automation, AI/ML workflows, and runtime control. Standard and Pro editions interface with Python, MATLAB, SUMO, and Wireshark. The Emulator connects simulations with real hardware and live applications, applying configured delay, loss, and error conditions. NetSim Cyber adds network and attack emulation for power-system cyber-physical testbeds and interfaces with listed power-system tools. Licensing can remain local through on-premises floating deployment, and cloud licensing exchanges only handshake data. NetSim runs on Windows; emulator setup specifies a dedicated Windows 10 or 11 machine.