The ROM Monitor software is also known as ROMMON, boot software, boot image, or boot helper. Although it is distributed with routers that use the Cisco IOS XE software, the ROMMON is a separate program from the Cisco IOS XE software. During normal startup, ROMMON initializes the router, and then, the control passes to the Cisco IOS XE software.
When you connect a terminal to the router that is in ROMMON mode, the ROMMON command-line interface (CLI) prompt is displayed.
Access the ROMMON mode to perform these tasks:
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Specify config-register value to use for the next boot up
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Boot a valid IOS XE image
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Bypass NVRAM settings and config-register value for password recovery
![Hardware Installation Guide for the Cisco 1000 Series Integrated Services Router - ROM Monitor Overview and Basic Procedures [Cisco 1100 Integrated Services Router] (1)](https://i0.wp.com/www.cisco.com/content/dam/en/us/td/i/templates/note.gif "Hardware Installation Guide for the Cisco 1000 Series Integrated Services Router - ROM Monitor Overview and Basic Procedures [Cisco 1100 Integrated Services Router] (1)") Note | After the Cisco IOS XE software boots up, ROMMON is no longer in use. |
Environmental Variables and the Configuration Register
Two primary connections exist between ROMMON and the Cisco IOS XE software: the ROMMON environment variables and the configuration register.
The ROMMON environment variables define the location of the Cisco IOS XE software and describe how to load it. After ROMMON has initialized the router, it uses the environment variables to locate and load the Cisco IOS XE software.
The configuration register is a software setting that controls how a router starts up. One of the primary uses of the configuration register setting is to control whether the router starts in ROMMON mode or Administration EXEC mode. The configuration register is set in either ROMMON mode or Administration EXEC mode as needed. You can set the configuration register using the Cisco IOS XE software prompt when you need to use ROMMON mode. When maintenance in ROMMODE mode is complete, change the configuration register back so that the router reboots with the Cisco IOS XE software.
Access ROMMON Mode with a Terminal Connection
When the router is in ROMMODE mode, you can access the ROMMODE software only from a terminal connected directly to the console port of the card. Because the Cisco IOS XE software (EXEC mode) is in operatiion, the nonmanagement interfaces are not accessible. Therefore, all Cisco IOS XE software resources are unavailable.
Network Management Access and ROMMON Mode
ROMMON mode is a router mode, not a mode within the Cisco IOS XE software. The ROMMON software and the Cisco IOS XE software are two separate programs that run on the same router. At any given time, the router is running one of these programs, but it never runs both at the same time.
One area that can be confusing when using ROMMON and the Cisco IOS XE software is the area that defines the IP configuration for the Management Ethernet interface. Most users are comfortable with configuring the Management Ethernet interface in the Cisco IOS XE software. When the router is in ROMMON mode, however, the router is not running the Cisco IOS XE software, therefore, Management Ethernet interface configuration is not available.
When you want to access other devices, such as a TFTP server, while in ROMMON mode on the router, you must configure the ROMMON variables with IP access information.
For more information on ROMMON and Basic Procedures, refer to the Cisco ISR1000 Software Configuration Guide.
![Hardware Installation Guide for the Cisco 1000 Series Integrated Services Router - ROM Monitor Overview and Basic Procedures [Cisco 1100 Integrated Services Router] (2024)](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mP8/h8AAvMB+NzmkbcAAAAASUVORK5CYII=)