A Networker Blog.-

This is a new feature in 12.3 that enables the router to perform a reboot using the IOS image currently running in DRAM. Having this capability greatly reduces boot time (no decompression or copying from slow flash) and reduces down-time when the router is returned to ROM by a bug. It also enables us to reboot the router even if we don’t have a valid IOS image in flash.

However, for warm-reboot to be active the router has to be cold-rebooted at least once after it’s configured.

With this command “warm-boot”, comes two options. The first is “count” which configures the maximum number of warm-reboots after which the router will perform a cold reboot. The second keyword is “uptime” which configures the time after which warm-reboot will be safe in case of a crash.

R1(config)#warm-reboot ?
Count Set max number of continuous warm reboots
uptime Set the uptime after which warm reboot is safe in case of a crash

To confirm if warm-boot is active, use the command “show warm-reboot”. You can also test it by issuing a “reload warm”. See below:

R1#show warm-reboot
Warm Reboot is enabled
Maximum warm reboot count is 5
Uptime after which warm reboot is safe in case of a crash is 5 (min)
Warm reboot can take place only after the next power cycle or reload.

So we reload the routers, after that,

R1#show warm-reboot
Warm Reboot is enabled
Maximum warm reboot count is 5
Uptime after which warm reboot is safe in case of a crash is 5 (min)
Statistics:
0 warm reboots due to crashes and 0 warm reboots due to requests have taken
place since the last cold reboot
2422 KB taken up by warm reboot storage

R1#reload warm
Proceed with reload? [confirm]