These are virtual multilayer switch images taken directly from Cisco Modeling Labs. They run as QEMU/KVM virtual machines inside the GNS3 VM. They offer the most stable, bug-free environment for advanced Layer 2 and Layer 3 switching features. 2. IOL / IOU (IOS on Linux / Unix)
| Approach | How It Works | What It Delivers | Best For | |----------|-------------|------------------|----------| | | Official Cisco VIRL/CML appliance | Full L2 switching features via QEMU | Advanced labs with real switch behavior | | IOU (IOS on Unix) | Lightweight Linux-based Cisco internal tool | L2 and L3 switching via Linux process | Complex topologies on limited hardware | | Etherswitch Router | Router with switching module enabled | Basic VLANs, STP (no advanced features) | Simple switching needs or legacy labs | cisco switch ios image download for gns3 install