When upgrading a series router to IOS-XE 17.x (such as 17.3 or 17.6), you often need to first update the ROMMON to version 17.3(1r) . This specific package, asr1000-rommon.173-1r.spa.pkg , ensures the hardware is compatible with the newer software architecture. Upgrade Procedure
copy tftp://server/asr1000-rommon.173-1r.spa.pkg harddisk: upgrade rommon harddisk:asr1000-rommon.173-1r.spa.pkg reload asr1000-rommon.173-1r.spa.pkg
show rommon
One engineer recently upgraded an ASR1002 from ROMMON 152-3r to 173-1r because the router failed to boot IOS-XE 17.9.x. The old ROMMON didn’t recognize the new ESP module. After the upgrade, the router booted perfectly. Cisco ASR 1000 When upgrading a series router to IOS-XE 17