第一步：登录路由器，用show version查看版本R3#show versionCisco Internetwork Operating System SoftwareIOS (tm) 2500
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第一步：登录路由器，用show version查看版本
R3#show version
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(19), RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2006 by cisco Systems, Inc.
Compiled Fri 12-May-06 08:15 by evmiller
Image text-base: 0x0307DE48, data-base: 0x00001000
ROM: System Bootstrap, Version 11.0(10c), SOFTWARE
BOOTLDR: 3000 Bootstrap Software (IGS-BOOT-R), Version 11.0(10c), RELEASE SOFTWA
RE (fc1)
R3 uptime is 2 hours, 32 minutes
System returned to ROM by power-on
System image file is "flash:c2500-is-l.123-19.bin"
cisco 2500 (68030) processor (revision N) with 14336K/2048K bytes of memory.
Processor board ID 13567188, with hardware revision 00000000
Bridging software.
X.25 software, Version 3.0.0.
1 Ethernet/IEEE 802.3 interface(s)
2 Serial network interface(s)
32K bytes of non-volatile configuration memory.
16384K bytes of processor board System flash (Read ONLY)
Configuration register is 0x2142
第二步：修改路由的寄存器值
R3#conf
Configuring from terminal, memory, or network [terminal]?
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)#config-register 0x2102 （config-register 后面跟上想修改的寄存器值）
2500以下为：o/r 0x2142
2500以上为 confreg 0x2142
0x2100 Rom monitor
0x2101 从rom 启动
0x2102 从 flash 启动，同时读取Nvram中的startup-config（这里中默认的值）
0x2142 从flash启动，不读取startup-config，常用于进行密码恢复
