Table Of Contents

Reserve Memory for Console Access

Contents

Information About Reserve Memory for Console Access

More Reserved Memory for Console Access Benefit

Guidelines for Increasing Reserved Memory for Console Access

How to Configure Reserve Memory for Console Access

Configuring Reserve Memory for Console Access

Examples

Configuration Examples for Reserve Memory for Console Access

Configuring Reserve Memory for Console Access: Example

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Command Reference

Feature Information for Reserve Memory for Console Access

Reserve Memory for Console Access

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First Published: July, 22, 2002

Last Updated: June 28, 2007, for Release 12.4(15)T

The Reserve Memory for Console Access feature implements command-line interface (CLI) and software enhancements that allow you to reserve sufficient memory to log in to the router console and perform administrative tasks and troubleshooting. These enhancements give administrators the ability to log in to the router in any situation even when the router is running low on memory.

Finding Feature Information in This Module

Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for Reserve Memory for Console Access" section.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

Contents

•Information About Reserve Memory for Console Access

•How to Configure Reserve Memory for Console Access

•Configuration Examples for Reserve Memory for Console Access

•Additional References

•Command Reference

•Feature Information for Reserve Memory for Console Access

Information About Reserve Memory for Console Access

Before you increase the amount of memory reserved for console access, you should understand the following concepts:

•More Reserved Memory for Console Access Benefit

•Guidelines for Increasing Reserved Memory for Console Access

More Reserved Memory for Console Access Benefit

Before the release of Cisco IOS 12.0(22)S software, you could not access the router console if a router was low on memory or was heavily fragmented. To maintain routers at optimum performance levels, you need to be able to access the console and perform troubleshooting when necessary.

With the release of the Reserve Memory for Console Access feature, the benefit is that you can reserve sufficient memory to log in to the router console and perform administrative tasks and troubleshooting in any situation, even when the router is running low on memory or is heavily fragmented.

Guidelines for Increasing Reserved Memory for Console Access

Cisco IOS software reserves a default of 256 kilobyte (KB) of memory for console access. You can increase the reserved memory through the use of the memory reserved console command provided by the Reserve Memory for Console Access feature.

The guideline we suggest for using the command is to configure a value greater than three times the number of the used bytes in NVRAM. You can obtain the number of used bytes in NVRAM from the output of the dir nvram: command. For example, if the total number of used bytes of NVRAM displayed in the command dir nvram: output is 129016 bytes, the nearest kilobyte value rounded off is 129 KB. This value multiplied by 3 is 387 KB. Following the guideline, you would enter 387 as the value for the number-of-kilobytes argument in the memory reserved console command. You can increase the reserved memory for console access to a maximum of 4096 KB.

To display the current operational size of the memory reserved for the console, you can use the show memory console reserved command.

How to Configure Reserve Memory for Console Access

This section provides contains the following procedure:

•Configuring Reserve Memory for Console Access.

Configuring Reserve Memory for Console Access

Perform this task to configure reserve memory for console access. You may need to increase the amount of memory reserved for console access if the router is low on memory or is heavily fragmented. Increasing the memory allows console access to perform troubleshooting or other administrative tasks to maintain routers at optimum performance levels.

SUMMARY STEPS

1. enable

2. configure terminal

3. memory reserve console number-of-kilobytes

4. exit

5. show memory console reserved

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. •Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	memory reserved console number-of-kilobytes Example: Router(config)# memory reserved console 512	Increases the amount of memory reserved for console access. •The number-of-kilobytes argument is the amount of memory to be reserved in kilobytes. Valid values are 1 to 4096 KB.
Step 4	exit Example: Router(config)# exit	Exits to privileged exit mode.
Step 5	show memory console reserved Example: Router# show memory console reserved	Displays the actual amount of memory that has been reserved.

Examples

The following is sample output from the show memory console reserved command:

Router# show memory console reserved

Memory reserved for console is 201400

Configuration Examples for Reserve Memory for Console Access

This section provides the following configuration example:

•Configuring Reserve Memory for Console Access: Example.

Configuring Reserve Memory for Console Access: Example

The following example shows how to increase the reserve memory for console access to 1024 KB:

enable

! 

configure terminal

!

memory reserved console 1024

end

The following example shows how to disable the increase in reserved memory for the console access:

enable

!

configure terminal

!

no memory reserved console

end

Additional References

The following sections provide references related to the Reserve Memory for Console Access feature.

Related Documents

Related Topic	Document Title
Cisco IOS Configuration Fundamentals commands	Cisco IOS Configuration Fundamentals Command Reference, Release 12.2
Cisco IOS Configuration Fundamentals configuration tasks and concepts	Cisco IOS Configuration Fundamentals Configuration Guide, Release 12.2

Standards

Standard	Title
No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.	—

MIBs

MIB	MIBs Link
No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.	To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs

RFCs

RFC	Title
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified for this feature.	—

Technical Assistance

Description	Link
The Cisco Technical Support & Documentation website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.	http://www.cisco.com/techsupport

Command Reference

The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS Configuration Fundamentals Command Reference at http://www.cisco.com/en/US/docs/ios/fundamentals/command/reference/cf_book.html. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.

•memory reserved console

•show memory console reserved

Feature Information for Reserve Memory for Console Access

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Cisco IOS software images are specific to a Cisco IOS software release, a feature set, and a platform. Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

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Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release. Unless noted otherwise, subsequent maintenance releases of that Cisco IOS software release also support that feature.

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Table 1 Feature Information for Reserve Memory for Console Access 

Feature Name	Releases	Feature Information
Reserve Memory for Console Access	12.0(22)S 12.2(28)SB 12.4(15)T	The Reserve Memory for Console Access feature implements command-line interface (CLI) and software enhancements that allow you to reserve sufficient memory to log in to the router console and perform administrative tasks and troubleshooting. These enhancements give administrators the ability to log in to the router in any situation even when the router is running low on memory. In 12.0(22)S, this feature was introduced. In 12.2(28)SB, this feature was integrated into a Cisco IOS 12.2SB release. In 12.4(15)T, this feature was integrated into a Cisco IOS 12.2T release. The following sections provide information about this feature: •More Reserved Memory for Console Access Benefit •Guidelines for Increasing Reserved Memory for Console Access •Configuring Reserve Memory for Console Access The following commands were modified by this feature: memory reserved console, show memory console reserved.

Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.

© 2007 Cisco Systems, Inc. All rights reserved.