Official and legal images are generally obtained through paid Cisco subscriptions rather than public free downloads.

The primary legal source for NX-OSv images is a Cisco Modeling Labs (CML) subscription (formerly VIRL). This provides access to .qcow2 and .vmdk files designed for hypervisors.

While the marketplace provides the appliance template ( .gns3a file), it does not include the actual operating system image. You must download the template from the GNS3 Marketplace and then provide your own legally acquired image file during installation. System Requirements for Nexus 7k in GNS3

It is highly recommended to run these images within the GNS3 VM on VMware Workstation or ESXi rather than locally on Windows.

Nexus images are resource-intensive virtual machines and require a robust environment:

KVM acceleration must be enabled in your BIOS and hypervisor settings. Cisco NX-OSv - GNS3

A minimum of 3072 MB (3 GB) per Nexus instance is required. CPU: At least 1 to 2 vCPUs .

NXOSv is a reference platform for an implementation of the Cisco Nexus operating system, based on the Nexus 7000-series platforms,