ROM Monitor OverviewThis chapter provides an overview of ROM Monitor concepts and operations. For instructions on how to perform various tasks in ROM Monitor (ROMMON) mode, see the other chapters in this book. Show
This chapter includes these main topics: Information About ROM MonitorThe ROM Monitor is a bootstrap program that initializes the ASR 9000 hardware and boots the Cisco IOS XR software when you power on or reload a router. A version of the ROM Monitor software exists on each card and is factory supplied. The ROM Monitor program provides an initial power-on environment for each card. If the Cisco IOS XR software is rebooted or unable to run, the corresponding card returns to the ROM Monitor mode. When you connect a terminal to a card that is in the ROM Monitor mode, the ROM Monitor CLI prompt is displayed. Cisco ASR 9000 Series Router PromptThe ROM Monitor software is known by many names. It is sometimes called ROMMON because of the CLI prompt in ROM Monitor mode. The ROM Monitor software is also called the boot software, boot image, or boot helper. Although it is distributed with routers that use the Cisco IOS XR software, ROM Monitor is a separate program from the Cisco IOS XR software. During normal startup, the ROM Monitor initializes the cards, and then control passes to the Cisco IOS XR software. After the Cisco IOS XR software takes over, ROM Monitor is no longer in use. Understanding the Role of the Route Switch Processor (RSP) CardThe Cisco ASR 9000 Series Router contains series of chassis slots, each of which can hold one of several types of line cards (LCs). Two slots in the chassis are reserved for route switch processors (RSP) cards that provide the central point for chassis provisioning and management. The active RSP for the owner SDR is called the Designated Shelf Controller (DSC). This card performs system-wide functions. If the active RSP card is placed in ROM Monitor mode, it is no longer running the Cisco IOS XR software. If a standby RSP card is available, then the standby RSP card resumes router operations. If both the RSP cards are not available or if the active RSP (previously standby) is also placed in the ROM Monitor mode, router operations will stop. Designated Secure Domain Router Shelf Controller (DSDRSC)When the Designated Secure Domain Router Shelf Controller (DSDRSC) in an SDR is placed in ROM Monitor mode, the router operations are transferred to the standby DSDRSC (if available). If both the primary and standby DSDRSCs are in ROM Monitor mode, then the router operations cease because the Cisco IOS XR software is no longer running. Accessing ROM Monitor Mode on the RSP CardIn most situations, you interact with the ROM Monitor mode only on the RSP cards. The active RSP card contains the administration configuration for the entire system and distributes the required software to all the other nodes in the router. All the tasks in this document describe ROM Monitor mode accessed through the RSP card for the system. The line cards have its own ROM Monitor software which can be upgraded using the RSP FPD upgrade operation, if required. Environmental Variables and the Configuration RegisterTwo primary connections exist between ROM Monitor and the Cisco IOS XR software: the ROM Monitor environment variables and the configuration register. The ROM Monitor environment variables define the location of the Cisco IOS XR software and describe how to load it. After ROM Monitor has initialized the card, it uses the environment variables to locate and load the Cisco IOS XR software. The common environment variables are BOOT, IP_ADDRESS, DEFAULT_GATEWAY, TFTP_FILE, TURBOBOOT and SUBNET_MASK. The configuration register is a software setting that controls how a card starts up. One of the primary uses of the configuration register is to control whether the card starts in ROM Monitor mode or Administration EXEC mode. The configuration register is set in either ROM Monitor mode or Administration EXEC mode as needed. Typically, you set the configuration register using the Cisco IOS XR software prompt on the active RSP when you need to use ROM Monitor mode. When the maintenance in ROM Monitor mode is complete, you change the configuration register so the card reboots with the Cisco IOS XR software.
Accessing ROM Monitor Mode with a Terminal ConnectionWhen an RSP is in ROM Monitor mode, you can access the ROM Monitor software only from a terminal connected directly to the console port of the card. Because the Cisco IOS XR software (EXEC mode) is not operating, the nonmanagement interfaces (such as GigabitEthernet interfaces) are not accessible. Basically, all Cisco IOS XR software resources are unavailable. The hardware is there, but no configuration exists to make use of the hardware. Network Management Access and ROM Monitor ModeSome people get confused when they start to use ROM Monitor mode. It is important to remember that ROM Monitor mode is a router mode, not a mode within the Cisco IOS XR software. It is best to remember that ROM Monitor software and the Cisco IOS XR 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 ROM Monitor and the Cisco IOS XR software is the area that defines the IP configuration for the Management Ethernet interface. Most router users get comfortable with configuring the Management Ethernet interface in the Cisco IOS XR software. When the router is in ROM Monitor mode, however, the router is not running the Cisco IOS XR software, so that Management Ethernet interface configuration is not available. To access other devices, such as a TFTP server, while in ROM Monitor mode on the Cisco ASR 9000 Series Router, you must configure the ROM Monitor variables with IP access information. Entering ROM Monitor ModeThe following sections describe two ways to enter ROM Monitor mode: PrerequisitesBefore you place a RSP card in ROM Monitor mode, verify that the system is in a steady state:
After you have verified that the system is in a stable state, you can enter ROM Monitor mode by setting the configuration register setting and entering the reload command, as described in the following steps: Resetting the Configuration Register and Reloading a RSP Card to ROM Monitor ModeIn normal operating conditions, it should not be necessary to use ROM Monitor mode. If you do find it necessary to place a RSP card in ROM Monitor mode, make sure that the system is in a steady state and that you are prepared for the consequences of a system reload. SUMMARY STEPS
DETAILED STEPS
Verifying the Router State: ExampleThe following example shows the redundancy roles of both RSPs and shows that both are operating in IOS XR RUN state: Placing the RSP Cards in ROM Monitor Mode: ExampleThe following example shows how to place the RSP in the ROM Monitor mode: Manually Halting the Initialization Process During System ReloadTo force the RSP card to stop loading and enter ROM Monitor mode, press Ctrl-C when you see the following message: This message usually appears during the first 20 seconds of system startup. Press the Ctrl-C key combination immediately. It may be necessary to press the Ctrl-C keys repeatedly during this time to ensure that the initialization process stops and the system enters ROM Monitor mode. This ends your Telnet session to the console or auxiliary port. This operation can be performed only from a terminal directly connected to the RSP card console port. For more information, see the “Connecting and Communicating with the Router” section in Cisco ASR 9000 Series Aggregation Services Router Getting Started Guide.
ROM Monitor CommandsThe commands in the ROM Monitor mode are different from those available in the Cisco IOS XR software. You can run ROM Monitor commands only while in ROM Monitor mode, and you cannot run Cisco IOS XR software commands. This section includes the following topics: Commonly Used ROM Monitor CommandsThe table below summarizes the commands commonly used in ROM Monitor. For specific instructions on using these commands, refer to the relevant procedure in this document. Table 1. Commonly Used ROM Monitor Commands
Displaying the Available ROM Monitor CommandsThe table below describes the available help commands for ROM Monitor mode. Table 2. Help Commands in ROMMON
Displaying the Available ROM Monitor Commands: ExamplesThe following example shows what appears when you enter the ? command on a Cisco ASR 9000 Series Router: The following example shows the parameters for the dir (directory) command: The following example shows what appears when you enter the version command at the Cisco ASR 9000 Series Router ROM Monitor mode prompt: Changing the ROM Monitor PromptYou can change the prompt in ROM Monitor mode by using the PS1= command as shown in the following example: Changing the prompt is useful if you are working with multiple routers in ROM Monitor at the same time. This example specifies that the prompt is ASR9K_ROMMON B followed by the line number. Displaying the Configuration Register SettingTo display the current configuration register setting, enter the confreg command without parameters as follows: The configuration register setting is labeled Virtual Configuration Register. Enter the no command to avoid changing the configuration register setting. Environment VariablesThe ROM Monitor environment variables define the attributes of the ROM Monitor, such as the IP address for an RSP control Ethernet port or the location of the Cisco IOS XR software and describe how to load it. Environmental variables are entered like commands and are always followed by the equal sign (=). Environment variable settings are entered in capital letters, followed by a definition. For example: Under normal operating conditions, you do not need to modify these variables. They are cleared or set only when you need to make changes to the way ROM Monitor operates. Frequently Used Environmental VariablesThe table below shows the main ROM Monitor environmental variables. For instructions on how to use these variables, see the relevant instructions in this document.
Displaying Environment Variable SettingsTo display the current environment variable settings, enter the set command at the ROM Monitor mode prompt : Entering Environment Variable SettingsEnvironment variable settings are entered in capital letters, followed by a definition. The following example shows the environmental variables used to configure the control Ethernet port on a Cisco ASR 9000 Series Router: Saving Environment Variable SettingsTo save the current environment variable settings, enter the sync command:
Clearing Environment Variable SettingsTo clear the environment variable settings, enter the unset command: To make the change permanent, use the sync command.
Viewing Chassis Serial NumbersThe chassis serial number can be read from an RSP that is running in ROM Monitor mode. Viewing the chassis number from the RSP may be necessary if the physical label is missing or damaged.
Exiting ROM Monitor ModeTo exit ROM Monitor mode, you must change the configuration register and reset the RSP. Resetting the Configuration Register Using PromptsTo change the configuration register settings in the ROM Monitor mode, enter the confreg command at the ROM Monitor mode. Entering this command displays the configuration summary and the prompts used to change the configuration. In ROM Monitor mode, you can change the configuration register value using the configuration register prompts, as shown in this procedure. SUMMARY STEPS
DETAILED STEPS
Resetting to EXEC Mode or MBI Validation ModeTo exit the ROM Monitor mode and reset to EXEC mode, enter the confreg command at the ROM Monitor mode prompt. Respond to prompts as instructed. Exiting ROM Monitor Mode: ExamplesThe following example shows how to enable ROM Monitor mode at the next system boot: The following example shows how to enter the minimum boot image (MBI) validation mode or the EXEC mode of Cisco IOS XR software at the next system boot: To reset to the MBI validation mode or EXEC mode, select 2 as the boot type. Enter the reset command to boot the RSP in the EXEC mode.
Attaching to Primary RSP from Standby RSPYou must follow these steps in order to attach to the primary RSP from standby RSP:
Additional ReferencesThe following sections provide references related to the ROM Monitor. Related Documents
Technical Assistance
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Which of the following refers to the keyboard combination that forces a soft boot or jump to ROM monitor?
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