새로 들어온 Network Device 의 IOS Upgrade를 하던 중 이미지도 정상적으로 Upload 되고 boot system 도 정상적으로 지정이 되었는데 Reload 를 하면 이전 이미지로 booting 이 되는 난감한 상황 속에서 원인을 찾았네요. 정상적으로 사용되는 config-register 의 값은 0x2102 인데 0x2 로 지정되어 있더군요.

config-register 값은 보통 show version 시 마지막 줄에서 확인 할 수 있어요.

ex )

R1>sh ver
Cisco Internetwork Operating System Software
IOS (tm) 2600 Software (C2691-IS-M), Version 12.3(22), RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2007 by cisco Systems, Inc.
Compiled Wed 24-Jan-07 17:17 by ccai
Image text-base: 0x60008AF4, data-base: 0x61C6A000

ROM: ROMMON Emulation Microcode
ROM: 2600 Software (C2691-IS-M), Version 12.3(22), RELEASE SOFTWARE (fc2)

R1 uptime is 1 minute
System returned to ROM by unknown reload cause - suspect boot_data[BOOT_COUNT] 0x0, BOOT_COUNT 0, BOOTDATA 19
System image file is "tftp://255.255.255.255/unknown"

cisco 2691 (R7000) processor (revision 0.1) with 120832K/10240K bytes of memory.
Processor board ID XXXXXXXXXXX
R7000 CPU at 80MHz, Implementation 39, Rev 2.1, 256KB L2, 512KB L3 Cache
Bridging software.
X.25 software, Version 3.0.0.
SuperLAT software (copyright 1990 by Meridian Technology Corp).
2 FastEthernet/IEEE 802.3 interface(s)
4 Serial network interface(s)
DRAM configuration is 64 bits wide with parity enabled.
55K bytes of non-volatile configuration memory.
65536K bytes of ATA System CompactFlash (Read/Write)

Configuration register is 0x2102


Configuration register 값에 대한 정리.

사용자 삽입 이미지

Software Configuration Bit Meanings
Bit No. Hex Meaning
00-03 0x0000-0x000F Boot Field
06 0x0040 Ignore NVM contents
07 0x0080 OEM bit enabled
08 0x0100 Break disabled
10 0x0400 IP broadcast with all zeros
11-12 0x0800-0x1000 Console line speed
13 0x2000 Boot default ROM software if network boot fails
14 0x4000 IP broadcasts do not have net numbers
15 0x8000 Enable diagnostic messages and ignore NVM contents

Explanation of Boot Field (Configuration Register Bits 00-03)
Boot Field Meaning
00 Stays at the system bootstrap prompt
01 Boots system image on EPROM
02-F Specifies a default netboot filename

Enables boot system commands that override default netboot filename


Default Boot Filenames
Action/Filename Bit 3 Bit 2 Bit 1 Bit 0
Bootstrap monitor 0 0 0 0
ROM software 0 0 0 1
cisco2-igs 0 0 1 0
cisco3-igs 0 0 1 1
cisco4-igs 0 1 0 0
cisco5-igs 0 1 0 1
cisco6-igs 0 1 1 0
cisco7-igs 0 1 1 1
cisco10-igs 1 0 0 0
cisco11-igs 1 0 0 1
cisco12-igs 1 0 1 0
cisco13-igs 1 0 1 1
cisco14-igs 1 1 0 0
cisco15-igs 1 1 0 1
cisco16-igs 1 1 1 0
cisco17-igs 1 1 1 1

Configuration Register Settings for Broadcast Address Destination
Bit 14 Bit 10 Address (<net> <host>)
off off <ones> <ones>
off on <zeros> <zeros>
on on <net> <zeros>
on off <net> <ones>

System Console Terminal Baud Rate Settings
Baud Bit 12 Bit 11
9600 0 0
4800 0 1
1200 1 0
2400 1 1

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