Cisco pyATS vs GNS3

Cisco pyATS is a Python framework for network testing, automation, and validation, available free under the Apache 2.0 license. It supports sanity, feature, solution, system, and scale test and verification workflows, with reusable data-driven tests ranging from simple checks to complex asynchronous suites. Genie libraries provide device connectivity, parsers, APIs, platform-agnostic feature models, reusable test cases, and a YAML-driven test runner. Built-in device libraries cover Cisco IOS, IOS XE, IOS XR, NX-OS, and ASA; plugins and extensions can add other platforms. Connections can use CLI, NETCONF, or RESTCONF. XPRESSO manages test suites, environments, testbeds, resources, live test views, and archived results with comparisons and analytics. It supports on-demand, bundled, and scheduled runs through Jenkins and Docker backends. Cisco also documents Ansible community integrations and out-of-the-box RobotFramework support. pyATS runs on Linux and macOS and supports self-hosted deployment. Cisco says more than 75% of its codebase is open source on GitHub. Email support is best-effort and usually receives a reply within a day.

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.