Symptom

Occasionally, during a ROMMON firmware upgrade, we can encounter a failed checksum, leading to the failure of the upgrade process: csg-rtp-ovld#up ro fi bootflash:isr4400_dev_rommon_SSA.pkg r0 Chassis model ISR4451-X/K9 has a single rom-monitor. Upgrade rom-monitor Target copying rom-monitor image file Booted : 0 Selected : 0 Reset Reason: 1 Secure upgrade of the ROMMON image will occur after a reload. Copying ROMMON environment... 262144+0 records in 262144+0 records out 262144 bytes (262 kB, 256 KiB) copied, 0.675992 s, 388 kB/s Switching to ROM 1 Updating ROMMON environment... 262144+0 records in 262144+0 records out 262144 bytes (262 kB, 256 KiB) copied, 16.6496 s, 15.7 kB/s 262144+0 records in 262144+0 records out 262144 bytes (262 kB, 256 KiB) copied, 1.41592 s, 185 kB/s FAILURE: ROMMON Variable data failed verification check.

Conditions

This has mainly been seen on ISR 4k routers, though other prerequisite conditions are unknown.

Workaround

This issue doesn't occur every time, so subsequent upgrade attempts may be successful.

Further Problem Description