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.
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]