Cisco Catalyst 4500 Series - Page 171

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Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 3 Configuring the Switch for the First Time
Modifying the Supervisor Engine Startup Configuration
Table 3-3 lists the meaning of each of the software configuration memory bits. Table 3-4 defines the boot
field.
Table 3-3 Software Configuration Register Bits
Bit Number
1
1. The factory default value for the configuration register is 0x2101. This value is a combination of the following: binary bit 13,
bit 8 = 0x0100 and binary bits 00 through 03 = 0x0001. See Table 3-4.
Hexadecimal Meaning
00 to 03 0x0000 to 0x000F Boot field (see Table 3-4)
04 0x0010 Unused
05 0x0020 Bit two of console line speed
06 0x0040 Causes system software to ignore NVRAM contents
07 0x0080 OEM
2
bit enabled
2. OEM = original equipment manufacturer.
08 0x0100 Unused
09 0x0200 Unused
10 0x0400 IP broadcast with all zeros
11 to 12 0x0800 to 0x1000 Bits one and zero of Console line speed (default is 9600 baud)
13 0x2000 Loads ROM monitor after netboot fails
14 0x4000 IP broadcasts do not have network numbers
Table 3-4 Explanation of Boot Field (Configuration Register Bits 00 to 03)
Boot Field Meaning
00 Stays at the system bootstrap prompt (does not autoboot).
01 Boots the first file in onboard flash memory.
02 Auto boots using image(s) specified by the BOOT environment variable. If more than one
image is specified, the switch attempts to boot the first image specified in the BOOT
variable. As long as the switch can successfully boot from this image, the same image is
used on a reboot. If the switch fails to boot from the image specified in the BOOT variable,
the switch tries to boot from the next image listed in the BOOT variable. If the end of the
BOOT variable is reached without the switch booting successfully, the switch attempts the
boot from the beginning of the BOOT variable. The autoboot continues until the switch
successfully boots from one of the images specified in the BOOT variable.
03 Unsupported or unused. If the boot field is set to this value, a warning message is
displayed, indicating that you must check and reenter the correct value.
04
1
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.