Upload Catalyst switch IOS using XMODEM

XMODEM is simple file transfer protocol which allows you to transfer data when both devices use modem. In this case, means you have no operating system on switch flash or it`s corrupted, thus unusable and you need XMODEM to upload your operating system.

First, verify that you entered ROMMON. If dialog starts with switch: you are in ROMMON. Next is to verify files in flash memory by typing dir flash: . If there is no IOS type following:

copy xmodem: flash:c3550-i5q3l2-mz.121-9.EA1c.bin

As you can see, I’m copying IOS for Cisco Catalyst 3550. Hit enter, and on terminal emulation software find file transfer option (Slide 1).

Upload Catalyst switch IOS using XMODEM

Slide 1

Select XMODEM and then Send option. From browse windows select same file you entered in command line above. Select Open (Slide 2).

Upload Catalyst switch IOS using XMODEM

Slide 2.

Transfer will start and you will be able to overview transfer process. It will be slow so configure highest possible baud rate.

When transfer is complete verify output, it should inform you is process successful or not. Now, type following:

boot flash:c3550-i5q3l2-mz.121-9.EA1c.bin

This command will boot up your switch with new IOS.

One more thing: I was using Extra Putty as my terminal emulation software, because standard Putty does’t have this service. You can use SecureCRT also.

I hope this tutorial was informative to you and I’m looking forward to your comments and feedback.


Dejan Dzodan

Dejan Dzodan

IT professional for more then 15 years, mostly in financial institutions but with experience in ISP and retail. Proven in networking and overall infrastructure projects. Cisco instructor.

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