This document explains how to recover a Cisco Catalyst switch when its software becomes corrupted. This document covers these Catalyst models that run Catalyst OS (CatOS) software with the Supervisor Engine:
Catalyst 4500/4000 series (which includes the 2948G, 2980G, and 4912G, but not the -L3 series)
Catalyst 5500/5000 series (which includes Catalyst 5500, 5505, 5509, and some of the 2900 series models, but not the XL series)
Catalyst 6500/6000 series
Refer to these documents for recovery procedures for switches that this document does not cover:
There are no specific requirements for this document.
The information in this document is based on these software and hardware versions:
Catalyst 4500/4000 series switch that runs CatOS
Catalyst 5500/5000 series switch that runs CatOS
Catalyst 6500/6000 series switch that runs CatOS
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
Refer to Cisco Technical Tips Conventions for more information on document conventions.
These switches run their software from RAM, after they load the software image from a Flash device. If all Flash images get corrupted or deleted, the switch cannot boot properly. In this condition, the switch generally falls back into a ROM monitor (ROMmon) mode, which has limited feature capability. This document explains how to download a new image and recover the switch from this situation.
During a software upgrade, you can issue the delete command in order to delete the old image from Flash and load the new image. The new image transfer can fail because of network/TFTP server problems. Or an unintentional deletion of the old image from the Flash device can occur. Still, you can issue the undelete command in order to recover the image. However, this recovery is possible only under these circumstances:
When you use the delete command in order to delete an image from the Flash, the image is permanently deleted from Flash. You can recover the image with use of the undelete command. This is applicable to Catalyst 4500/4000, 5500/5000, and 6500/6000 series switches.
In the case of the Catalyst 4500/4000, if you reload the switch after deletion of the image, you can still recover the deleted image in ROMmon mode. Issue the undelete ROM monitor command. The commands in this list are supported in ROMmon mode for only Catalyst 4500/4000 series switches that run CatOS release 6.1 and later:
For details on these commands, refer to these documents:
If these options do not work with your Catalyst 4500/4000, 5500/5000, and 6500/6000 series switches, follow the recovery procedures in this document.
Note: You can use TFTP in order to transfer software image files from a PC to your device. This document uses output from the Cisco TFTP Server application. Cisco has discontinued this application and no longer supports it. If you do not have a TFTP server, obtain any third-party TFTP server application from another source.
The Catalyst 4500/4000 has an onboard bootflash Flash system that is used to store image files. During normal bootup, the Supervisor Engine typically loads a software image from Flash. The Flash is no longer needed for switch operation after an image is loaded in RAM. You can then use the traditional copy tftp flash command in order to upgrade the software while the switch is up and operational. However, you can encounter a problem with the software that you currently have in Flash and can be unable to fully boot the switch. Or the switch can end up in ROMmon for some reason and you must get the switch back up. In such cases, you can now boot from the network (TFTP) server with use of the Recovery Procedure in this document.
Before you proceed to the recovery procedure, make sure that you do not have any valid files in the bootflash:. Issue the dir bootflash: command from the rommon> mode in order to determine if there are any files in the bootflash:. If a valid file exists, issue the boot bootflash: filename command in order to attempt to bring up the switch. As the Background Information section notes, you can undelete a deleted file from ROMmon on these switches. You can issue the undelete bootflash: filename command in order to undelete the file. The file can then be used to boot the switch. If you have no valid file in the bootflash, proceed to the Recovery Procedure.
Note: For more information on how to connect a console to your switch, as well as how to manage and upgrade software, see the Related Information