GNS3 vs Ostinato

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.

Ostinato generates and customizes network traffic, or replays PCAP files, to help validate throughput, QoS, multicast, routing, switching, protocol behavior, and network performance. Users can edit supported protocol headers, set frame sizes, and create custom headers with hexdumps or scripts. PCAP replay can preserve or alter packet timing, loop traffic, or reorder packets. Native protocols include Ethernet, VLAN, QinQ, IPv4/IPv6, UDP, stateless TCP, ICMP, ARP/NDP, IGMP/MLD, and GRE; other methods can support headers such as MPLS and VXLAN. Reports show transmit and receive statistics, per-stream packet loss, and latency and jitter measured with software timestamps. A Python API supports stream and scenario creation, run control, counter collection, and CI/CD integration. Ostinato lists GNS3, EVE-NG, Cisco CML, and Containerlab as supported lab environments, and says it works on AWS and Azure cloud VMs. It runs on Linux, macOS, Windows, and self-hosted or API setups. Plans start at $12 a month billed annually; an active subscription is required.