原本想採用官方推薦的方法進行升級，不過感覺不怎麼方便。官方的升級方法地址如下：
http://www.cisco.com/en/US/docs/wireless/access_point/conversion/lwapp/upgrade/guide/lwapnote.html
麻煩之處有幾點：1.每臺胖AP都必須登錄後配置用戶密碼、啓動TELNET、配置接口地址等信息；2.雖然軟件可以一次同時升級6臺設備，但前提是你有一定的網絡環境纔可以；……
由於以上的幾點，我採用了另外的一種方法進行胖AP升級到瘦AP。以下是整個升級過程：
準備工作：
1.Cisco TFTP Server程序並配置電腦IP爲：10.0.0.2/255.0.0.0
2.準備瘦AP的IOS文件：如c1240-k9w7-tar.default；下載位置：
http://www.cisco.com/public/sw-center/index.shtml
操作過程：
按住AP上的MODEL按鈕， 接通AP電源， 不要鬆開MODEL鍵，直至指示燈變爲藍色、×××到粉色，在啓動的過程中你會看到AP有一個默認IP地址爲10.0.0.1, 而且會發送廣播（發向255.255.255.255）尋找TFTP服務器，試圖從TFTP服務器下載相對應的IOS（搜索與AP上默認文件名相同名稱的文件，注意看AP上的信息，類似於“c1140-k9w7-tar.default”），
1242 瘦AP IOS ：c1240-k9w7-tar.124-25d.JA.tar
1242 胖AP ios： c1240-rcvk9w8-tar.124-21a.JA2.tar
方法二： 用console線連接到AP上，啓動後，能進入config terminal模式的就是胖AP，不能進去(也就是不可配置)的就是瘦AP。
AP升級日誌：
Initializing ethernet port 0...
Reset ethernet port 0...
Reset done!
ethernet link up, 100 mbps, full-duplex
Ethernet port 0 initialized: link is up
button is pressed, wait for button to be released...
出現以下信息表示正在升級
process_config_recovery: set IP address and config to default 10.0.0.1
process_config_recovery: p_w_picpath recovery
p_w_picpath_recovery: Download default IOS tar p_w_picpath tftp://255.255.255.255/c1240-k9w7-tar.default
examining p_w_picpath...
extracting info (273 bytes)
Image info:
Version Suffix: rcvk9w8-
Image Name: c1240-rcvk9w8-mx
Version Directory: c1240-rcvk9w8-mx
Ios Image Size: 2632192
Total Image Size: 2632192
Image Feature: WIRELESS LAN|LWAPP|RECOVERY
Image Family: C1240
Wireless Switch Management Version: 3.0.51.0
Extracting files...
c1240-rcvk9w8-mx/ (directory) 0 (bytes)
extracting c1240-rcvk9w8-mx/c1240-rcvk9w8-mx (2622783 bytes)....................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
................................................................................
.....................................................................
extracting c1240-rcvk9w8-mx/info (273 bytes)
extracting info.ver (273 bytes)
Deleting current version: flash:/c1240-k9w7-mx.124-3g.JA1...done.
New software p_w_picpath installed in flash:/c1240-rcvk9w8-mx
Configuring system to use new p_w_picpath...done.
Requested system reload in progress...download took about 108 seconds
Loading "flash:/c1240-rcvk9w8-mx/c1240-rcvk9w8-mx"...###########################
################################################################################
################################################################################
######################################################################
File "flash:/c1240-rcvk9w8-mx/c1240-rcvk9w8-mx" uncompressed and installed, entr
y point: 0x3000
executing...
按住MODE鍵，再插入電源開機。
出現button is pressed, wait for button to be released...時鬆開MODE鍵，貌似還要不停的敲回車，才能進 set command 模式，要不然會examining p_w_picpath...。
在出現AP：後，使用set IP_ADDR 10.0.0.1（設IP地址），set NETMASK 255.255.255.0（設掩碼），tftp_init （格式化）。
在使用上述命令後，再使用TFTP從電腦上把文件拷下來，命令：tar -xtract tftp://10.0.0.2/c1240-k9w7-tar.124-10b.JA3.tar flash:
下載文件成功後，AP會自動安裝。
安裝完成後，輸入boot重啓AP。
Note Your wireless device configuration is not changed when using the CLI to reload the p_w_picpath file.
STEP 1: Open the CLI using a connection to the wireless device console port.
STEP 2: Reboot the wireless device by removing power and reapplying power.
STEP 3: Let the wireless device boot until it begins to inflate the p_w_picpath. When you see these lines on the CLI, press Esc:
Loading "flash:/c350-k9w7-mx.v122_13_ja.20031010/c350-k9w7-mx.v122_13_ja.20031010"
...###########################################################################
################################################################################
################################################################################
####################
STEP 4: When the ap: command prompt appears, enter the set command to assign an IP address, subnet mask,
and default gateway to the wireless device.
Note You must use upper-case characters when you enter the IP-ADDR, NETMASK, and DEFAULT_ROUTER options with the set command.
Your entries might look like this example:
ap: set IP_ADDR 192.168.133.160
ap: set NETMASK 255.255.255.0
ap: set DEFAULT_ROUTER 192.168.133.1
STEP 5: Enter the tftp_init command to prepare the wireless device for TFTP.
ap: tftp_init
STEP 6: Enter the tar command to load and inflate the new p_w_picpath from your TFTP server. The command must include this information:
? the -xtract option, which inflates the p_w_picpath when it is loaded
? the IP address of your TFTP server
? the directory on the TFTP server that contains the p_w_picpath
? the name of the p_w_picpath
? the destination for the p_w_picpath (the wireless device Flash)
Your entry might look like this example:
ap: tar -xtract tftp://192.168.130.222/p_w_picpaths/c350-k9w7-tar.122-13.JA1.tar flash:
STEP 7: When the display becomes full, the CLI pauses and displays --MORE--. Press the spacebar to continue.
extracting info (229 bytes)
c350-k9w7-mx.122-13.JA1/ (directory) 0 (bytes)
c350-k9w7-mx.122-13.JA1/html/ (directory) 0 (bytes)
c350-k9w7-mx.122-13.JA1/html/level1/ (directory) 0 (bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/appsui.js (558 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/back.htm (205 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/cookies.js (5027 bytes).
extracting c350-k9w7-mx.122-13.JA1/html/level1/forms.js (15704 bytes)...
extracting c350-k9w7-mx.122-13.JA1/html/level1/sitewide.js (14621 bytes)...
extracting c350-k9w7-mx.122-13.JA1/html/level1/config.js (2554 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/stylesheet.css (3215 bytes)
c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/ (directory) 0 (bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/ap_title_appname.gif (1422 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_1st.gif (1171 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_cbottom.gif (318 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_current.gif (348 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_last.gif (386 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_last_filler.gif (327 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_last_flat.gif (318 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_button_nth.gif (1177 bytes)
extracting c350-k9w7-mx.122-13.JA1/html/level1/p_w_picpaths/apps_leftnav_dkgreen.gif (869 bytes)
-- MORE --
Note If you do not press the spacebar to continue, the process eventually times out and the wireless device stops inflating the p_w_picpath.
STEP 8: Enter the set BOOT command to designate the new p_w_picpath as the p_w_picpath that the wireless device uses when it reboots. The wireless device creates a directory for the p_w_picpath that has the same name as the p_w_picpath, and you must include the directory in the command. Your entry might look like this example:
ap: set BOOT flash:/c350-k9w7-mx.122-13.JA1/c350-k9w7-mx.122-13.JA1
STEP 9: Enter the set command to check your bootloader entries.
ap: set
BOOT=flash:/c350-k9w7-mx.122-13.JA1/c350-k9w7-mx.122-13.JA1
DEFAULT_ROUTER=192.168.133.1
IP_ADDR=192.168.133.160
NETMASK=255.255.255.0
STEP 10: Enter the boot command to reboot the wireless device. When the wireless device reboots, it loads the new p_w_picpath.
ap: boot