Recovering a Corrupt Cisco IOS Image on a Catalyst Switch

Lab Objectives

•   Boot the switch into SWITCH ROM mode.
•   Initialize the flash file system.
•   OPTIONAL – Format the flash file system if needed.
•   Set the baud rate to 115200 to increase xmodem transfer speed and decrease time required to restore the IOS Image.
•   Copy the Cisco IOS Image via xModem to Flash:
•   Set the boot parameter to the new image name located in Flash:
•   Unset the baud so that it defaults back to 9600.
•   Boot the switch and verify that the switch boots properly.

Lab Instruction

Recovering the Cisco IOS Image on a Cisco Catalyst Series switch is quite a bit different and more of an “old school” way of doing an IOS image recovery. Unfortunately fixed configuration switches that do not support removable Compact Flash cards like the Cisco 4500 and Cisco 6500 Series switches use xModem to restore a corrupt or missing IOS image to flash:

Step 1. Boot your switch into switch ROM mode. This typically involves holding down the STAT button on the front of the switch when plugging in the power.

Once you’ve booted your switch into Switch ROM mode you’ll be see the following dispatch;

Boot Sector Filesystem (bs) installed, fsid: 2 Base ethernet MAC Address: 00:14:f2:d2:41:80 Xmodem file system is available. The password-recovery mechanism is enabled. The system has been interrupted prior to initializing the flash filesystem. The following commands will initialize the flash filesystem, and finish loading the operating system software: flash_init boot switch:

Step 2. Once you’ve booted into Switch ROM mode you’ll need to initialize the flash file system by executing the flash_init command as shown below;

switch: flash_init Initializing Flash... flashfs[0]: 1 files, 1 directories flashfs[0]: 0 orphaned files, 0 orphaned directories flashfs[0]: Total bytes: 15998976 flashfs[0]: Bytes used: 12474880 flashfs[0]: Bytes available: 3524096 flashfs[0]: flashfs fsck took 10 seconds. ...done Initializing Flash. switch:

Step 3 – OPTIONAL – If your image is corrupted you may need to format your flash file system by executing the format flash: command as shown below;

Switch: format flash: Are you sure you want to format "flash:" (all data will be lost) (y/n)?y flashfs[0]: 0 files, 1 directories flashfs[0]: 0 orphaned files, 0 orphaned directories flashfs[0]: Total bytes: 7741440 flashfs[0]: Bytes used: 1024 flashfs[0]: Bytes available: 7740416 flashfs[0]: flashfs fsck took 12 seconds. Filesystem "flash:" formatted Switch:

Step 4. To speed up the xModem file transfer speed you’ll need to set the console line BAUD rate to 115200 by executing the set BAUD 115200. If you do this you’ll need to disconnect your console session and change the serial line speed from 9600 to 115200. However if you do not set the BAUD to 115200 your file transfer can take up to 3 hours.

switch: set BAUD 115200 ÿ

Step 5. Once setting the BAUD rate and reconnecting to the console line of your Cisco switch you’re ready to copy the IOS image via xModem to the switch’s flash memory by executing the copy xmodem: flash:filename.bin as shown below;

switch: copy xmodem: flash:c3560-ipservicesk9-mz.122-53.SE.bin Begin the Xmodem or Xmodem-1K transfer now... CCC Starting xmodem transfer. Press Ctrl+C to cancel. Transferring c3560-ipservicesk9-mz.122-53.SE.bin... 100% 12181 KB 6 KB/s 00:31:56 0 Errors ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................................................................. ................. File "xmodem:" successfully copied to "flash:c3560-ipservicesk9-mz.122-53.SE.bin" switch:

Step 6. Once the IOS image is copied into flash you’ll need to update the BOOT parameter by executing the set BOOT flash:filename.bin command as shown below;

switch: set BOOT flash:c3560-ipservicesk9-mz.122-53.SE.bin

Step 7. Once the boot parameter has been set you can now set the BAUD rate back to the default 9600bps by executing the command unset BAUD. Note when doing this you’ll need to disconnect your current console connection and change the baud speed on your terminal emulator from 115200 back to 9600.

switch: unset BAUD ÿ

Step 8 is the last step which is to boot the switch and verify that the switch successfully boots the IOS image placed into flash from xMODEM. Execute the boot command to load the IOS image specified in the boot parameter as shown below;

switch: boot Loading "flash:/c3560-ipservicesk9-mz.122-53.SE.bin"...@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ File "flash:/c3560-ipservicesk9-mz.122-53.SE.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 Cisco IOS Software, C3560 Software (C3560-IPSERVICESK9-M), Version 12.2(53)SE, RELEASE SOFTWARE (fc2) Technical Support: http://www.cisco.com/techsupport Copyright (c) 1986-2009 by Cisco Systems, Inc. Compiled Sun 13-Dec-09 15:45 by prod_rel_team Image text-base: 0x01000000, data-base: 0x02E00000 Initializing flashfs... flashfs[1]: 1 files, 1 directories flashfs[1]: 0 orphaned files, 0 orphaned directories flashfs[1]: Total bytes: 15998976 flashfs[1]: Bytes used: 12474880 flashfs[1]: Bytes available: 3524096 flashfs[1]: flashfs fsck took 1 seconds. flashfs[1]: Initialization complete....done Initializing flashfs. Checking for Bootloader upgrade.. not needed POST: CPU MIC register Tests : Begin POST: CPU MIC register Tests : End, Status Passed POST: PortASIC Memory Tests : Begin POST: PortASIC Memory Tests : End, Status Passed POST: CPU MIC interface Loopback Tests : Begin POST: CPU MIC interface Loopback Tests : End, Status Passed POST: PortASIC RingLoopback Tests : Begin POST: PortASIC RingLoopback Tests : End, Status Passed POST: Inline Power Controller Tests : Begin POST: Inline Power Controller Tests : End, Status Passed POST: PortASIC CAM Subsystem Tests : Begin POST: PortASIC CAM Subsystem Tests : End, Status Passed POST: PortASIC Port Loopback Tests : Begin POST: PortASIC Port Loopback Tests : End, Status Passed Waiting for Port download...Complete This product contains cryptographic features and is subject to United States and local country laws governing import, export, transfer and use. Delivery of Cisco cryptographic products does not imply third-party authority to import, export, distribute or use encryption. Importers, exporters, distributors and users are responsible for compliance with U.S. and local country laws. By using this product you agree to comply with applicable laws and regulations. If you are unable to comply with U.S. and local laws, return this product immediately. A summary of U.S. laws governing Cisco cryptographic products may be found at: http://www.cisco.com/wwl/export/crypto/tool/stqrg.html If you require further assistance please contact us by sending email to export@cisco.com. cisco WS-C3560-24PS (PowerPC405) processor (revision M0) with 131072K bytes of memory. Processor board ID CAT0928Z2EE Last reset from power-on 1 Virtual Ethernet interface 24 FastEthernet interfaces 2 Gigabit Ethernet interfaces The password-recovery mechanism is enabled. 512K bytes of flash-simulated non-volatile configuration memory. Base ethernet MAC Address : 00:14:F2:D2:D1:AF Motherboard assembly number : 73-9673-06 Power supply part number : 341-0029-03 Motherboard serial number : CAT09880NNZ Power supply serial number : LIT091091ZV Model revision number : M0 Motherboard revision number : A0 Model number : WS-C3560-24PS-S System serial number : CAT0911FAEE Top Assembly Part Number : 800-25861-03 Top Assembly Revision Number : A0 Version ID : V05 CLEI Code Number : COM1X1FARB Hardware Board Revision Number : 0x01 Switch Ports Model SW Version SW Image ------ ----- ----- ---------- ---------- * 1 26 WS-C3560-24PS 12.2(53)SE C3560-IPSERVICESK9-M Press RETURN to get started!