Hi Naveen,
The config register on the 3750 (and other desktop switches) is fixed at 0xF. It cannot be changed, but it is analogous to 0x2102 on other platforms in that it causes the switch to boot from flash, and load the saved config.text.
Config-Register is basically a hexadecimal or decimal value that represents the 16-bit configuration register value that will be used the next time the switch is restarted. The value range is from 0x0 to 0xFFFF (0 to 65535 in decimal).
The lowest four bits of the configuration register (bits 3, 2, 1, and 0) form the boot field. The boot field determines if the router boots manually, from ROM, or from Flash or the network.
About the values:
1· If you set the configuration register boot field value to 0x0, you must boot the operating system manually with the boot command.
2· If you set the configuration register boot field value to 0x1, the router boots using the default ROM software.
3· If you set the configuration register boot field to any value from 0x2 to 0xF, the router uses the boot field value to form a default boot filename for booting from a network server.
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_1_13/config/supcfg.htm#102199
Or
http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_2_31s/conf/supcfg.htm#wp10189900
Stays at the system bootstrap prompt (does not auto boot).
01
Boots the first system image in onboard Flash memory.
02 to 0F
Auto boots using image(s) specified by the BOOT environment variable. If more than one image is specified, the switch attempts to boot the first image specified in the BOOT variable. As long as the switch can successfully boot from this image, the same image will be used on a reboot. If the switch fails to boot from the image specified in the BOOT variable, the switch will try to boot from the next image listed in the BOOT variable. If the end of the BOOT variable is reached without the switch booting successfully, the switch attempts the boot from the beginning of the BOOT variable. The auto boot continues until the switch successfully boots from one of the images specified in the BOOT variable.
P.S. I have read the following document on configuration-register values
http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a008022493f.shtml
HTH
Regards
Inayath
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