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What is Rommon Mode

knaik99
Level 1
Level 1

in rommon mode ,when we login to switch then it is seen as below way--

switch:-----Right?

when switch does not find IOS in flash then it goes into Rommon mode ,right?

for going into Rommon mode,switch uses Mini IOS ,Right?

where is that mini IOS stored in switch ,please explain

5 Replies 5

Hi

 It is store by Cisco during the device manufacturing. All the necessary software to device function or recovery from a problem must be added during the device manufacturing as long as a initial IOS version. 

M02@rt37
VIP
VIP

Hello @knaik99,

When a switch cannot find a valid IOS image in its flash memory during the boot process, it will enter ROMmon mode. ROMmon (ROM Monitor) is a low-level software program stored in the switch's read-only memory (ROM). It provides a basic set of commands and functionalities that allow you to perform tasks such as booting the switch, recovering from a failed boot process, or troubleshooting.

The "Mini IOS" you mentioned is actually referred to as the "ROMmon image" or "bootstrap image." This image is a stripped-down version of the Cisco IOS software that is used to bootstrap the switch and load a full IOS image from another location, such as a TFTP server. The ROMmon image is stored in a separate section of the switch's memory known as the "bootflash."

The bootflash is a type of non-volatile memory, usually a flash memory chip, where the switch stores its ROMmon image along with other boot-related files. It is distinct from the main flash memory where the full IOS image and other files are stored.

When the switch enters ROMmon mode, it executes the ROMmon image from the bootflash memory. From there, you can use the ROMmon commands to perform various operations, such as loading a new IOS image, recovering a corrupted image, or setting boot parameters.

I think that the specific terminology and details may vary depending on the switch model and software version.

Best regards
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Where is Rommon image or bootstrap image stored i.e. in ROM or Bootflash?

the mini-IOS is save in same datafile that IOS save in.

cisco-ccna-ios-01.jpg

Leo Laohoo
Hall of Fame
Hall of Fame

The flash is divided into several "chambers" for which no one has access to but one.  

The ROMMON files are stored in one of them.  NO one has read access to them and only Cisco developers have read/write access to them.  

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