topic Re: configuration register is 0xf Why ? in Switching

configuration register is 0xf Why ?

williamsdo — Wed, 06 Mar 2019 10:57:58 GMT

Hello All, I have to reload 5 switches tonight the units are WS-C2960G-24TC-L known as LANBASE switches. My question is I have always been taught the config-reg should be 0x2102, but on these switches is is 0xF, does anyone know why Cisco has changed this and if so where I might be able to find a document describing this change? Thank you all.

Re: configuration register is 0xf Why ?

Jon Marshall — Sun, 14 Dec 2008 21:25:54 GMT

Sorry don't have a link to hand but the default configuration register setting on the 2960 switches is indeed 0xF and this cannot be changed. So you are okay to reload the switches.

Jon

Re: configuration register is 0xf Why ?

williamsdo — Sun, 14 Dec 2008 21:35:27 GMT

Thank you John, I wonder why no documents on Cisco.com about this, they should know how scarry reloading switches can be. Thank Again

Donald

Re: configuration register is 0xf Why ?

Pari Thiagasundaram — Mon, 15 Dec 2008 04:36:05 GMT

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:

Â· If you set the configuration register boot field value to 0x0, you must boot the

operating system manually with the boot command.

Â· If you set the configuration register boot field value to 0x1, the router boots using

the default ROM software.

Â· 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#1021

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_2_31s/conf/supcfg.htm#wp101

89900

Stays at the system bootstrap prompt (does not auto boot).

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.

Re: configuration register is 0xf Why ?

vishwancc — Mon, 15 Dec 2008 05:03:52 GMT

Hi ,

Nice reply

Chao

Vishwa