A Warm Reload.

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)


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]

*Jun 24 18:09:35.135: %SYS-5-RELOAD: Reload requested by console. Reload Reason: Reload Command.
Smart Init is disabled. IOMEM set to: 10

Using iomem percentage: 10

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Cisco IOS Software, 2800 Software (C2800NM-ADVENTERPRISEK9-M), Version 12.4(7a), RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport
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Cisco 2811 (revision 49.46) with 237568K/24576K bytes of memory.
Processor board ID FTX1009C5KL
2 FastEthernet interfaces
4 Serial(sync/async) interfaces
1 Virtual Private Network (VPN) Module
DRAM configuration is 64 bits wide with parity enabled.
239K bytes of non-volatile configuration memory.
62720K bytes of ATA CompactFlash (Read/Write)
Press RETURN to get started!

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