emulator within the GNS3 VM. It is highly stable and supports most CCNA/CCNP switching features (VLANs, STP, EtherChannel). You can get this by purchasing a Cisco Modeling Labs (CML) personal license. NM-16ESW Module
This is the most critical section of this guide. If you search Google for "Cisco Catalyst 2960 IOS GNS3 download," you will find hundreds of websites offering direct downloads (Mega, Mediafire, etc.).
If you own a physical 2960 switch, you can extract the .bin image from its flash memory.