15.4.1T supports:

| Aspect | 15.4.1T | Newer IOSv (15.8/15.9) | CSR1000v | | :--- | :--- | :--- | :--- | | | ~1 GB | ~2-3 GB | 4-6 GB | | Boot time | 30 sec | 40 sec | 90 sec | | Feature parity | Full MPLS, DMVPN | Same + VXLAN, Segment Routing (limited) | IOS XE (modern, but heavier) | | Community support | Huge (GNS3 forums, INE, etc.) | Moderate | Large | | License cost | Same (contract needed) | Same | Expensive for production |

In the world of network engineering, few tools are as valuable as a reliable, feature-rich software image for emulation and testing. For decades, Cisco’s Internetwork Operating System (IOS) has been the gold standard, but the transition from physical hardware to virtualized networking has introduced a new ecosystem of images. One filename, in particular, stands out for engineers working with GNS3, EVE-NG, and other virtualization platforms: .

delete /force /recursive flash:<old-image.bin>