I86bilinuxadventerprisek9ms1541tantigns3bin -

. Without this text file containing a host-specific license key, the image will fail to boot with a "License not found" error. Layer 2 vs. Layer 3 : While the file name you mentioned is an L3 (Router) image, Cisco IOU is also famous for providing L2 (Switch)

| Check | Command | |-------|---------| | | ping <upstream‑router> | | Routing protocols | show ip ospf neighbor , show bgp summary , show eigrp neighbors | | Interface status | show interfaces status | | License health | show license status | | CPU/Memory | show processes cpu , show memory statistics | | Log for errors | show logging (look for %SYS-5-RELOAD or any %SYS-2-... warnings) | i86bilinuxadventerprisek9ms1541tantigns3bin