上周被害苦了，所以请教了许多高手，按照以下的详细步骤升级你的IOS肯定又快又管用，希望对大家有点帮助！
　　
　　
　　QuickTip added by adhawkin on Mon Apr 30 12:11:36 PDT 2002
　　Recovery from booting to rommon
　　Introduction: What does this document describe? How to recover from botting into rommon mode on 3600 series routers. What problem is the customer having that this document will solve? Customer copied an IOS image that required more flash than they had available on their 3640 router.
　　Versions: What hardware and software versions did you use to develop this document? Customer was suing 11.2(16) and wanted to upgrade to 12.1(4.5)
　　
　　Use this field to input your configuration steps or
　　problem resolution.
　　The steps below outline how to connect and download another image using
　　XMODEM through the console port of the router.
　　How to download an image using xmodem when routers 3600 and 2600 goes into
　　ROMMON prompt?
　　Problem:- The router is in ROMMON prompt and when it is reloaded it again
　　goes into ROMMON prompt.
　　Solution:-
　　To solve the above problem, you can download an image to the 2600 and 3600
　　using the console port of the router.
　　The procedure uses the default console speed of 9600 bits per second.
　　Xmodem is a slow transfer protocol. Increasing the console speed (which is
　　possible
　　for the Cisco 2600 and 3600 series routers) helps decrease the time it
　　takes to do the xmodem file transfer.
　　3600 / 2600 in rommon
　　1- rommon > b ---------- to boot first image in flash mem
　　2- rommon > dir flash: ---------- list the files on the device
　　3- rommon > meminfo ---------- to see memory information
　　You are in rommon and
　　1- when "b" is typed the router comes back in rommon.
　　2- dir flash: reveals an invalid check sum.
　　3- So the last solution is to download an image using xmodem
　　When in ROMMON mode, follow the procedure below Using the ROMMON confreg
　　utility.
　　rommon 2 > confreg
　　do you wish to change the configuration? y/n [n]: y
　　enable "diagnostic mode"? y/n [n]: n
　　enable "use net in IP bcast address"? y/n [n]: n
　　disable "load rom after netboot fails"? y/n [n]: n
　　enable "use all zero broadcast"? y/n [n]: n
　　enable "break/abort has effect"? y/n [n]: n
　　enable "ignore system config info"? y/n [n]: n
　　change console baud rate? y/n [n]: y
　　enter rate: 0 = 9600, 1 = 4800