近期升级2台AP 1602i 1142N 全部使用电源模块供电，对其进行胖Ap转瘦AP，但操作中发现按MODE模式或者正常配置ip进去全部无法连接到TFTP服务器，经多次尝试，只需现用的flash版本删掉，即可重新TFTP获取新的IOS，具体步骤如下：
ap#dir
Directory of flash:/
2 -rwx 321726 Apr 25 2002 02:53:27 +00:00 crashinfo_20020425-025324
3 -rwx 1048 Apr 25 2002 04:41:14 +00:00 private-multiple-fs
4 -rwx 347860 Apr 25 2002 02:52:14 +00:00 crashinfo_20020425-025211
6 -rwx 220 Mar 1 2002 00:00:06 +00:00 env_vars
7 drwx 256 Mar 1 2002 00:11:00 +00:00 c1140-k9w7-mx.124-21a.JA1
155 -rwx 332858 Apr 25 2002 02:54:31 +00:00 crashinfo_20020425-025427
156 -rwx 339520 Apr 25 2002 02:55:51 +00:00 crashinfo_20020425-025548
157 -rwx 333434 Apr 25 2002 02:57:02 +00:00 crashinfo_20020425-025659
158 -rwx 323027 Apr 25 2002 03:02:28 +00:00 crashinfo_20020425-030225
159 -rwx 352748 Apr 25 2002 04:00:12 +00:00 crashinfo_20020425-040009
160 -rwx 354734 Apr 25 2002 04:26:02 +00:00 crashinfo_20020425-042559
162 -rwx 5 Apr 25 2002 04:37:49 +00:00 private-config
32385024 bytes total (24130560 bytes free)
查看先用IOS版本
ap#sh version
Cisco IOS Software, C1140 Software (C1140-K9W7-M), Version 12.4(21a)JA1, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2009 by Cisco Systems, Inc.
Compiled Wed 16-Sep-09 18:09 by prod_rel_team
ROM: Bootstrap program is C1140 boot loader
BOOTLDR: C1140 Boot Loader (C1140-BOOT-M) Version 12.4(23c)JA3, RELEASE SOFTWARE (fc1)
ap uptime is 7 minutes
System returned to ROM by watchdog timer expired
System image file is "flash:/c1140-k9w7-mx.124-21a.JA1/c1140-k9w7-mx.124-21a.JA1"
删除先用版本IOS
/recursive 删除指定文件夹下的所有文件和子文件夹 /force 删除而不给出提示 ap#delete /recursive /force flash:/c1140-k9w7-mx.124-21a.JA1 ap#dir Directory of flash:/ 2 -rwx 321726 Apr 25 2002 02:53:27 +00:00 crashinfo_20020425-025324 3 -rwx 1048 Apr 25 2002 04:41:14 +00:00 private-multiple-fs 4 -rwx 347860 Apr 25 2002 02:52:14 +00:00 crashinfo_20020425-025211 6 -rwx 220 Mar 1 2002 00:00:06 +00:00 env_vars 155 -rwx 332858 Apr 25 2002 02:54:31 +00:00 crashinfo_20020425-025427 156 -rwx 339520 Apr 25 2002 02:55:51 +00:00 crashinfo_20020425-025548 157 -rwx 333434 Apr 25 2002 02:57:02 +00:00 crashinfo_20020425-025659 158 -rwx 323027 Apr 25 2002 03:02:28 +00:00 crashinfo_20020425-030225 159 -rwx 352748 Apr 25 2002 04:00:12 +00:00 crashinfo_20020425-040009 160 -rwx 354734 Apr 25 2002 04:26:02 +00:00 crashinfo_20020425-042559 162 -rwx 5 Apr 25 2002 04:37:49 +00:00 private-config 32385024 bytes total (29672960 bytes free)
已经删除掉了，现在可以进入MODE模式下升级
首先把电脑ip地址设置成10.0.0.2 255.0.0.0 把固件名称改成下面提示的版本（断电后按住MODE键加电，看到提示下面，灯一直亮红色放手，如果更改完c1140-k9w7-tar.default，设备会自动进行升级，这里tftp32搭建略过）
button is pressed, wait for button to be released...
button pressed for 27 seconds
process_config_recovery: set IP address and config to default 10.0.0.1
process_config_recovery: image recovery
image_recovery: Download default IOS tar image tftp://255.255.255.255/c1140-k9w7-tar.default
image_recovery: Download default IOS tar image tftp://255.255.255.255/c1140-k9w7-tar.default
examining image...
extracting info (283 bytes)
Image info:
Version Suffix: k9w8-.153-3.JD
Image Name: c1140-k9w8-mx.153-3.JD
Version Directory: c1140-k9w8-mx.153-3.JD
Ios Image Size: 8550912
Total Image Size: 8847872
Image Feature: WIRELESS LAN|LWAPP
Image Family: C1140
Wireless Switch Management Version: 8.3.102.0
Extracting files...
如果瘦AP也可以按最后一部操作，基本相同。