Network Router User Manual

C-2

Cisco 2600 Series Routers Hardware Installation Guide

OL-2171-06

Appendix C Configuration Register

Changing Configuration Register Settings

You might want to modify the value in the configuration register to perform the following tasks:

• Recover a lost password

• Change the console data rate

• Enable or disable the Break function

• Manually boot the operating system using the b command at the ROM monitor prompt

• Force the router to automatically boot its system image in flash memory, or boot in accordance with

any boot system commands stored in the router’s configuration file in NVRAM

You can change the configuration register from either the ROM monitor or the operating system

software. To change the configuration register from the ROM monitor, see the “Configuration Register

Commands” section on page B-7. To change the configuration register from the system software, do the

following:

Step 1 Connect a console terminal to the console port of the router as described in the “Connecting to the

Console Port” section on page 3-20, using the blue RJ-45 to DB-9 console adapter cable.

Note If you have a terminal with a DB-25 port, use an RJ-45 rollover cable and DB-25 adapter. The

RJ-45-to-DB-25 adapter (Cisco part number 29-0810-01) can be purchased from Cisco.

For information about cable pinouts, refer to the online document Cisco Modular Access Router Cable

Specifications. This document is available online and on the Cisco Documentation CD-ROM.

Step 2 Configure your terminal or terminal emulation software for 9600 baud (default), 8 data bits, no parity,

and 1 stop bit.

Step 3 Power on the router.

Step 4 When asked if you would like to enter the initial dialog, answer no:

Would you like to enter the initial dialog? [yes]: no

Your router is now in the normal operating mode.

Step 5 After a few seconds, you see the user EXEC prompt (Router>). Enter the enable command and your

password to enter privileged EXEC mode:

10 0x0400 IP broadcast with all zeros.

5, 11, 12 0x0020,

0x0800, 0x1000

Console line speed.

13 0x2000 Boots default ROM software if the network boot fails.

14 0x4000 IP broadcasts do not have net numbers.

15 0x8000 Enables diagnostic messages and ignores the contents

of NVRAM.

Table C-1 Configuration Bit Meanings (continued)

Bit

Number Hexadecimal Meaning