Cisco 12406 - Manual (Page 2)

Chapter 4 Troubleshooting the Installation
Performing Other Configuration Tasks
4-2
Cisco 12006 and Cisco 12406 Router Installation and Configuration Guide
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– 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 4-1 defines 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 Number
1
Hexadecimal
Value
Definition/Function
00 to 03 0x0000 to
0x000F Comprises the boot field for defining the source of
a default Cisco IOS software image required to run
the router
06 0x0040 Causes system software to ignore the contents of
NVRAM