GNS3 vs NetSim

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 is a browser-based simulator of Cisco networking hardware and software for certification training. Its preconfigured labs provide the materials needed to complete each objective. Learners can compare their configurations with expected configurations to identify mistakes and get instant feedback, while lab progress and history sync between devices. Labs run in a web browser on modern internet-capable devices without installation; supported systems include Linux, macOS, and Windows. Network Designer lets users create custom labs with complex topologies, devices, connections, annotations, imported icons, and saved device configurations. It is included with the listed certification-specific plans. NetSim also includes the IOS images needed for its labs, without requiring additional licensing of those materials. Listed lab packs cost $29 a year and include 10 or 16 guided labs. Certification plans cost $179 a year and list between 70 and 101 guided labs. Online licenses last one year from purchase and can be used without usage limits during that period.