switch not able go into the IOS

Unanswered Question
Aug 25th, 2008


have 1 3550 switch it not able to boot into the IOS, it always just keep on rebooting. However when go into the rommon, manually boot it, it will able boot into the IOS but when reload again the switch then it will again go to the reboot loop.

for more details pls refer to the attachment file.

Pls advice as this very urgent for me.

Thank you


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glen.grant Mon, 08/25/2008 - 10:14

You could try a new image , its possible the current image has become corrupted. Also check the imagename syntax with a "dir flash: command and copy and paste that image name into the boot statement so that you know it correct. Check that the cofig register is 0x2102 also.

gilbertthor Mon, 08/25/2008 - 15:53


i already change the new image and and paste that image name into the boot statement, but also fail to go into IOS. as what i know 3550 not able to set the config-register, is it am i correct?



johnakeating Mon, 08/25/2008 - 20:06

try re-formating the flash maybe it has been corrupted and downloading an IOS from cisco or another 3550 switch .

smothuku Mon, 08/25/2008 - 23:27

Hi Gilbert ,

Checkout the below links...


Configuration Register Changes and the Set of Boot Statements

Unlike some other Catalyst switches, there is no config-register command on the 3550. You cannot change the configuration register value from the default.

The 3550 automatically searches for a valid software image from which to boot. The search occurs even if you do not set a boot system statement. Set the boot statement anyway, as a precaution. The command to set a boot system statement is boot system flash: file_name .

You can specify multiple images in the boot statement if you separate the image names with a semicolon. The command is boot system flash: file1;file2 .

If you use a CMS image on the 3550, the Cisco IOS image (.bin file) extraction creates a directory for the image alone. The boot system command becomes boot system flash: directory/file_name .

The Software Upgrade Procedure for the 3550 Series Switches section of this document covers in detail the use of the boot system command.





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