Cisco IOS Recovery

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c3750[edit]

Example Issue[edit]

  • Issue: cannot boot, prompt is at switch:

<source lang=text>

  1. Example fail

switch: boot Loading "flash:/c3750-ipbasek9-mz.122-46.SE.bin"...flash:/c3750-ipbasek9-mz.122-46.SE.bin: no such file or directory

Error loading "flash:/c3750-ipbasek9-mz.122-46.SE.bin"

Interrupt within 5 seconds to abort boot process. Loading "flash:/c3750-ipbasek9-mz.122-55.SE6.bin"...@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ Error loading "flash:/c3750-ipbasek9-mz.122-55.SE6.bin"

Interrupt within 5 seconds to abort boot process. Boot process failed...

switch: dir flash </source>

  • Switch: c3750
  • IOS: c3750-ipbasek9-mz.122-55.SE1.bin


Requirements[edit]

  1. Have your .bin file stored locally (laptop)
  2. linux + minicom with working serial connection

Steps[edit]

  • Connect to switch - minicom 9600 8N1
  • CHANGE baud rate of switch (otherwise it will be hours to load a file)

<source lang=text>

set BAUD 115200

</source>


  • change minicom to 115200 8N1
  • ready switch to recieve file over xmodem

<source lang=text>

copy xmodem: flash:/<your IOS version filename>.bin

</source> <source>

  1. example

switch: copy xmodem: flash:/c3750-ipbasek9-mz.122-55.SE1.bin Begin the Xmodem or Xmodem-1K transfer now... C </source>


  • send the local .bin file with minicom through xmodem

<source lang=text> ctrl-a z s xmodem select file (hit space) enter to send file </source>


  • watch your .bin file load! It will still be slow, but not hours @ 9600

<source lang=text>

        +-----------[xmodem upload - Press CTRL-C to quit]------------+                                                                        

Press CTR|Sending c3750-ipbasek9-mz.122-55.SE1.bin, 94373 blocks: Give |

        |your local XMODEM receive command now.                       |                                                                        

.........|Xmodem sectors/kbytes sent: 54509/6813k | |

        |                                                             |                                                                        
        |                                                             |                                                                        

switch: | |

        |                                                             |                                                                        

switch: +-------------------------------------------------------------+ </source>


  • set baud rate back to 9600
otherwise you or someone else will be really confused when they next try to use it. Go back into the bootloader by power-cycling the switch and holding down the “Mode” button.

<source lang=text>

set BAUD 9600

</source>


  • type boot (may have to type boot flash:/<your cisco file>.bin

<source lang=text>

switch: boot Loading "flash:/c3750-ipbasek9-mz.122-46.SE.bin"...flash:/c3750-ipbasek9-mz.122-46.SE.bin: no such file or directory

Error loading "flash:/c3750-ipbasek9-mz.122-46.SE.bin"

Interrupt within 5 seconds to abort boot process. Loading "flash:/c3750-ipbasek9-mz.122-55.SE1.bin"...@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ File "flash:/c3750-ipbasek9-mz.122-55.SE1.bin" uncompressed and installed, entry point: 0x1000000 executing...

             Restricted Rights Legend

Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013.

          cisco Systems, Inc.
          170 West Tasman Drive
          San Jose, California 95134-1706

..... truncated </source>


  • Check that you can reboot OK without ending up in the bootloader again.


Other Tricks[edit]

  • If the switch is not going into the bootloader, you may be able to force it
Try power-cycling the Catalyst while holding the “Mode” button on the front in to get the bootloader.
  • file system needs to be initialzied
Type “flash_init” to initialise the filesystem. (In our case, this wasn’t necessary)
Type “load_helper” to load any helper files (in our case there weren’t any since we’d just wiped the flash).