Modifying The Boot Field And Using The Boot Command - Cisco Catalyst 4500 Series Software Configuration Manual

Modifying the Supervisor Engine Startup Configuration
Table 3-4
Boot Field Meaning
1
05
1
06
1. Note: Requires ROMMON version 15.0(1r)SG14 on Catalyst 4500-X Series Switches, and ROMMON version 15.1(1r)SG8

Modifying the Boot Field and Using the boot Command

The configuration register boot field determines whether the switch loads an operating system image
and, if so, where it obtains this system image. The following sections describe how to use and set the
configuration register boot field and the procedures you must perform to modify the configuration
register boot field. In ROMMON, to modify the configuration register and change boot settings, use the
the confreg command.
Bits 0 through 3 of the software configuration register contain the boot field.
The factory default configuration register setting for systems and spares is 0x2101. However, the
Note
recommended value is 0x0102.
When the boot field is set to either 00 or 01 (0-0-0-0 or 0-0-0-1), the system ignores any boot instructions
in the system configuration file and the following occurs:
•
•
•
If you set bootfield to a value between 0-0-1-0 and 1-1-1-1, you must specify a value in the boot system
Caution
command, else the switch cannot boot up and remains in ROMMON.
You can enter the boot command only or enter the command and include additional boot instructions,
such as the name of a file stored in flash memory, or a file that you specify for booting from a network
server. If you use the boot command without specifying a file or any other boot instructions, the system
boots from the default flash image (the first image in onboard flash memory). Otherwise, you can
instruct the system to boot up from a specific flash image (using the boot system flash filename
command).
You can also use the boot command to boot up images stored in the compact flash cards located in slot 0
on the supervisor engine.
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
3-28
Explanation of Boot Field (Configuration Register Bits 00 to 03) (continued)
Auto boots the image that is retrieved from a network-based source, that is, a DHCP server.
Depending on how you configure the DHCP boot file field, the system then retrives the
files from the specified remote (HTTP or TFTP) server.
If this fails, the system resorts to the method specified in boot field 01.
Auto boots the image that is retrieved from a network-based source, that is, a DHCP server.
Depending on how you configure the DHCP boot file field, the system then retrives the
files from the specified remote (HTTP or TFTP) server.
If this fails, the system resorts to the method specified in boot field 02.
on Catalyst 4500-E Series Switches.
When the boot field is set to 00, you must boot up the operating system manually by entering the
boot command at the system bootstrap or ROMMON prompt.
When the boot field is set to 01, the system boots the first image in the bootflash single in-line
memory module (SIMM).
When the entire boot field equals a value between 0-0-1-0 and 1-1-1-1, the switch loads the system
image specified by boot system commands in the startup configuration file.
Chapter 3 Configuring the Switch for the First Time