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Community Member

Config Register question

On a Cisco 2600 router, where does the router boot from when the register is set to 0x2101?

I know that 0x2000 boots to ROMMON and that 0x2002-200F looks for boot system commands and then Flash for a filename.

I've read conflicting information regarding 0x2101.

1) Configures the system to boot automatically from ROM

2) To boot from the first image in Flash

It looks like older router platforms use option 1 and newer higher-end platforms use option 2.


Community Member

Re: Config Register question

a boot register of 0000 (converted from hex to binary) should boot to rommon

0001 should boot the first valid image in onboard flash

0002 work through boot statements in order etc.

i have always found this to be the same on all platforms, new and old, high and low.

would also appreciate the update if this is not the case :)

Community Member

Re: Config Register question

Thanks for the input. Just for the record, I just tested my theory out. I changed the config register on a 1600, 1720, 2500 and 2600 to 0x2101 and rebooted them.

It looks like the older routers (1600 and 2500), do boot to ROM E.g., Router(boot)>

The newer routers (1700 and 2600) boot the first valid image in Flash.

I suspect this discrepancy to be linked to the version of ROM. The version of ROM on the 1600 and 2500 platforms are ver 11, and version 12 for the 1700 and 2600.

I would appreciate this if anyone can confirm this.

Thanks again.

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