Installing IOS Image via Xmodem

If you’ve gotten to the point where this needs to be done, chances are the IOS image on your current switch/router is completely jacked up and you’re sitting at either the “rommon:” prompt or the “switch:” prompt. The following instructions will be operating under that assumption.

First, connect with the standard cisco serial connection info (9600 – 8 – N – 1 – N).

Then type the following at the prompt:

switch: set BAUD 115200

Then you’ll need to reconnect with the baud rate of 115200. This will make the transfer go significantly faster.

Next lets start the copy:

switch: copy xmodem: flash:

Once you do this, it’ll be waiting to accept the file, simply start the xmodem transfer now using your terminal emulator and wait.. for a long long time.. It’ll tell you when it’s done.

When it’s completed, type the following to set the console baud rate back to normal:

switch: unset BAUD

Reconnect with the standard cisco serial connection info (listed above). Once you’ve done that, you can boot your new flash image

switch: boot flash:path-to.ios.image.bin

Providing your IOS image is good, it’ll boot up properly and you’re good to go. It is good practice to point to this file once your switch/router boots up using the “boot system flash:path-to.ios.image.bin” command in configuration mode, though it’s not always necessary.

Phil Pillera <ppillera [ a t ] gmail [ d o t ] com>