Cisco Systems OL-11497-03 manual Bit Number1, Value Definition/Function

Chapter 4 Troubleshooting the Installation

Performing Other Configuration Tasks

–Flash memory SIMM (NVRAM) on the RP

–Boot image stored within the operating environment, which you access by using an appropriate form of the boot command entered at the ROM monitor prompt (rommon>)

•Define a default boot filename.

•Enable or disable the Break function.

•Control broadcast addresses.

•Set the console terminal baud rate.

•Force an automatic boot using a boot image.

When you first power on the router, a boot image called the RP ROM monitor is executed, and the ROM monitor prompt (rommon>) is displayed. At this prompt, you have access to a limited set of commands that enable you to set values in the software configuration register and to perform other tasks.

The RP ROM monitor is loaded into the RP Flash ROM when the RP is manufactured. You can use it to boot the system from local Flash memory devices. The RP ROM monitor software can be upgraded in the field, if necessary.

•Read boot system commands from the configuration file stored in NVRAM. Table 4-1defines the bits in the software configuration register.

Caution To avoid confusion and possibly halting the system, remember that valid software configuration register values may be combinations of settings, rather than the individual settings listed in Table 4-1. For example, the factory default value 0x0102 for the software configuration register is a composite of several settings.

		Table 4-1	Software Configuration Register Bit Meanings
		Bit Number1	Hexadecimal
			Value	Definition/Function
		00 to 03	0x0000 to	Comprises the boot field for defining the source of
			0x000F	a default Cisco IOS software image required to run
				the router
06			0x0040	Causes system software to ignore the contents of
				NVRAM
	Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
4-2				OL-11497-03