How to Use XMODEM on a Switch Stuck in ROMMON
Xmodem is mostly an afterthought now for transferring files to a switch due to how slow the transfer speed is and the use of much faster methods such as TFTP, although there are still some uses for it. For instance some Cisco switches such as the IE2000 industrial switch cannot use TFTP when in ROMMON mode. This means that if the switch cannot boot into the IOS then the only option left is to use Xmodem to transfer a new IOS file to the switch. I am going to briefly explain what Xmodem is and then show in a few steps how to get an Xmodem transfer started in ROMMON mode for the IE2000. Xmodem is a half-duplex communication protocol that sends data through the serial console cable you have connected to the switch. Xmodem uses 128 byte packets with ACK/NACK responses and CRC for the data checking.
- The first thing you need to do is turn the switch on while pressing the express setup button on the switch with a paperclip or thumbtack. You need to hold the button in for around 10 seconds and then let go.
- After you let the button go you should now be in ROMMON mode. The easiest way to tell if you are in ROMMON mode is by looking at the switch prompt. If you see switch: as your prompt then you know you are in ROMMON.
- Once you are in ROMMON mode the next step is to initialize the flash on the switch using the flash_init command.
- Next you will then start the Xmodem transfer process. First use the command copy xmodem: flash: ie2000-universalk9-mz.150-2.EA1.bin. once this command has been applied the transfer will begin on the switches end. (note that the .bin file will be different for different switches and different versions of IOS.
- Now that the transfer is started on the switches side it also needs to be started on the computers side as well. You do this by going to the menu bar of your console program and click the transfer section and select send Xmodem. Then you just need to select the IOS file you want to transfer and the transfer will begin.
6. Now the transfer has been started correctly you will see a progress bar at the bottom giving you useful information such as how much data has been transferred and how fast it is being transferred.
7. Now that the transfer is done the only things left to do are check the flash to make sure the file was transferred and to boot to the new IOS.
8. Now that there is confirmation that the IOS has been successfully transferred to the flash you can now use the command boot flash: ie2000-universalk9-mz.150-2.EA1.bin to boot to the new IOS. And that’s it! Now your switch that was stuck in ROMMON can now boot correctly and can be configured.
Cody Hodges got his first computer at age five, which kick-started his love for technology. Growing up, his father was in the IT industry, and Cody was motivated to continue pursuing his passion. He went on to receive his Associate’s Degree in Computer and Information Science from ECPI University.
Cody started his time at ABS as an intern. After just six months, he was brought on as a full-time Network Engineer.