Loading IOS on a switch or router via the console

If the flash has been deleted / formatted and there is no IOS on the switch or router, you have to copy the new IOS via the console port.

On Windows using Tera Term

The following article explains the procedure loading the IOS image c2600-is-mz.122-15.ZJ2.bin on a cisco26xx router using Tera Term

rommon 1 > xmodem -c c2600-is-mz.122-15.ZJ2.bin
Do not start the sending program yet...
File size Checksum File name
18699016 bytes (0x11d5308) 0x7234 c2600-is-mz.122-15.ZJ2.bin (bad checksum: 0x6683)

WARNING: All existing data in bootflash will be lost! Invoke this application only for disaster recovery. Do you wish to continue? y/n [n]: y
Ready to receive file c2600-is-mz.122-15.ZJ2.bin ...

now send the file by clicking on the top menu: file-> transfer-> send-> xmodem - and chose the file from your local directory
the transfer should start now.

once the transfer has finished the flash will be erased and you will get a message like:
Erasing flash at 0x61780000.
this might take a while before it says something like:
program flash location 0x600d0000
which might also take a bit.....before it finally says:
'Download Complete!
and the router/switch should boot

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the following article explains the procedure loading the IOS immage c3550-ipbasek9-mz.122-40.SE.bin on a WS-C3550 series switch using Tera Term

switch: copy xmodem: flash:c3550-ipbasek9-mz.122-40.SE
Begin the Xmodem or Xmodem-1K transfer now...
CCC
now send the file by clicking on the top menu: file-> transfer-> send-> xmodem - and chose the file from your local directory
the transfer should start now.

CCCC............................................................................
................................................................................
................................................................................
................................................................................
............................................
File "xmodem:" successfully copied to "flash:c3550-ipbasek9-mz.122-40.SE.bin"

now you have to boot the image you copied:
switch: boot flash:c3550-ipbasek9-mz.122-40.SE.bin
Loading "flash:c3550-ipbasek9-mz.122-40.SE.bin"...############
Press RETURN to get started!
Switch>
you're done!!!!

On Linux using Minicom

Let's assume the image we want to load is named c3750-ipbasek9-mz.122-46.SE.bin

• Power on the switch while holding down the Mode button (or use any other method) to get to the switch: prompt.
• Type format flash: to format and check the filesystem of the flash.
• Type copy xmodem: flash:c3750-ipbasek9-mz.122-46.SE.bin
• Type Control-A followed by S
• Select the file you want to transfer
  • Choose xmodem
  • Choose Go To using the left/right arrow keys and type in the path to the directory containing IOS file (e.g. /home/lab/IOS)
  • Navigate to the file you want to transfer using the up/down arrow keys and select the file using the Space key.
  • Choose Okay using the left/right arrow keys and wait for the (very slow) transfer to finish
• Type boot to boot the switch.